diff --git a/apisix/balancer.lua b/apisix/balancer.lua
index 4be56fcc28aa..16cbd5d661b3 100644
--- a/apisix/balancer.lua
+++ b/apisix/balancer.lua
@@ -14,10 +14,11 @@
 -- See the License for the specific language governing permissions and
 -- limitations under the License.
 --
-local require     = require
-local balancer    = require("ngx.balancer")
-local core        = require("apisix.core")
-local ipairs      = ipairs
+local require           = require
+local balancer          = require("ngx.balancer")
+local core              = require("apisix.core")
+local priority_balancer = require("apisix.balancer.priority")
+local ipairs            = ipairs
 local set_more_tries   = balancer.set_more_tries
 local get_last_failure = balancer.get_last_failure
 local set_timeouts     = balancer.set_timeouts
@@ -40,12 +41,27 @@ local _M = {
 }
 
 
+local function transform_node(new_nodes, node)
+    if not new_nodes._priority_index then
+        new_nodes._priority_index = {}
+    end
+
+    if not new_nodes[node.priority] then
+        new_nodes[node.priority] = {}
+        core.table.insert(new_nodes._priority_index, node.priority)
+    end
+
+    new_nodes[node.priority][node.host .. ":" .. node.port] = node.weight
+    return new_nodes
+end
+
+
 local function fetch_health_nodes(upstream, checker)
     local nodes = upstream.nodes
     if not checker then
         local new_nodes = core.table.new(0, #nodes)
         for _, node in ipairs(nodes) do
-            new_nodes[node.host .. ":" .. node.port] = node.weight
+            new_nodes = transform_node(new_nodes, node)
         end
         return new_nodes
     end
@@ -56,7 +72,7 @@ local function fetch_health_nodes(upstream, checker)
     for _, node in ipairs(nodes) do
         local ok, err = checker:get_target_status(node.host, port or node.port, host)
         if ok then
-            up_nodes[node.host .. ":" .. node.port] = node.weight
+            up_nodes = transform_node(up_nodes, node)
         elseif err then
             core.log.error("failed to get health check target status, addr: ",
                 node.host, ":", port or node.port, ", host: ", host, ", err: ", err)
@@ -66,7 +82,7 @@ local function fetch_health_nodes(upstream, checker)
     if core.table.nkeys(up_nodes) == 0 then
         core.log.warn("all upstream nodes is unhealthy, use default")
         for _, node in ipairs(nodes) do
-            up_nodes[node.host .. ":" .. node.port] = node.weight
+            up_nodes = transform_node(up_nodes, node)
         end
     end
 
@@ -83,9 +99,15 @@ local function create_server_picker(upstream, checker)
 
     if picker then
         local up_nodes = fetch_health_nodes(upstream, checker)
-        core.log.info("upstream nodes: ", core.json.delay_encode(up_nodes))
 
-        return picker.new(up_nodes, upstream)
+        if #up_nodes._priority_index > 1 then
+            core.log.info("upstream nodes: ", core.json.delay_encode(up_nodes))
+            return priority_balancer.new(up_nodes, upstream, picker)
+        end
+
+        core.log.info("upstream nodes: ",
+                      core.json.delay_encode(up_nodes[up_nodes._priority_index[1]]))
+        return picker.new(up_nodes[up_nodes._priority_index[1]], upstream)
     end
 
     return nil, "invalid balancer type: " .. upstream.type, 0
diff --git a/apisix/balancer/chash.lua b/apisix/balancer/chash.lua
index f9dbdbbb470b..3b260a25932f 100644
--- a/apisix/balancer/chash.lua
+++ b/apisix/balancer/chash.lua
@@ -118,7 +118,15 @@ function _M.new(up_nodes, upstream)
 
             ctx.balancer_tried_servers[ctx.balancer_server] = true
             ctx.balancer_tried_servers_count = (ctx.balancer_tried_servers_count or 0) + 1
-        end
+        end,
+        before_retry_next_priority = function (ctx)
+            if ctx.balancer_tried_servers then
+                core.tablepool.release("balancer_tried_servers", ctx.balancer_tried_servers)
+                ctx.balancer_tried_servers = nil
+            end
+
+            ctx.balancer_tried_servers_count = 0
+        end,
     }
 end
 
diff --git a/apisix/balancer/ewma.lua b/apisix/balancer/ewma.lua
index e1b276273063..e9926dac6531 100644
--- a/apisix/balancer/ewma.lua
+++ b/apisix/balancer/ewma.lua
@@ -147,7 +147,7 @@ local function _ewma_find(ctx, up_nodes)
         return nil, "all upstream servers tried"
     end
 
-    peers = lrucache_trans_format(ctx.upstream_key, ctx.upstream_version, _trans_format, up_nodes)
+    peers = lrucache_trans_format(up_nodes, ctx.upstream_version, _trans_format, up_nodes)
     if not peers then
         return nil, 'up_nodes trans error'
     end
@@ -228,7 +228,15 @@ function _M.new(up_nodes, upstream)
         get = function(ctx)
             return _ewma_find(ctx, up_nodes)
         end,
-        after_balance = _ewma_after_balance
+        after_balance = _ewma_after_balance,
+        before_retry_next_priority = function (ctx)
+            if ctx.balancer_tried_servers then
+                core.tablepool.release("balancer_tried_servers", ctx.balancer_tried_servers)
+                ctx.balancer_tried_servers = nil
+            end
+
+            ctx.balancer_tried_servers_count = 0
+        end,
     }
 end
 
diff --git a/apisix/balancer/least_conn.lua b/apisix/balancer/least_conn.lua
index 1cfdbf9f9252..8923d1781d00 100644
--- a/apisix/balancer/least_conn.lua
+++ b/apisix/balancer/least_conn.lua
@@ -31,10 +31,7 @@ end
 
 function _M.new(up_nodes, upstream)
     local servers_heap = binaryHeap.minUnique(least_score)
-    local safe_limit = 0
     for server, weight in pairs(up_nodes) do
-        safe_limit = safe_limit + 1
-
         local score = 1 / weight
         -- Note: the argument order of insert is different from others
         servers_heap:insert({
@@ -50,8 +47,10 @@ function _M.new(up_nodes, upstream)
             local server, info, err
             if ctx.balancer_tried_servers then
                 local tried_server_list = {}
-                for i = 1, safe_limit do
+                while true do
                     server, info = servers_heap:peek()
+                    -- we need to let the retry > #nodes so this branch can be hit and
+                    -- the request will retry next priority of nodes
                     if server == nil then
                         err = "all upstream servers tried"
                         break
@@ -100,7 +99,13 @@ function _M.new(up_nodes, upstream)
             end
 
             ctx.balancer_tried_servers[server] = true
-        end
+        end,
+        before_retry_next_priority = function (ctx)
+            if ctx.balancer_tried_servers then
+                core.tablepool.release("balancer_tried_servers", ctx.balancer_tried_servers)
+                ctx.balancer_tried_servers = nil
+            end
+        end,
     }
 end
 
diff --git a/apisix/balancer/priority.lua b/apisix/balancer/priority.lua
new file mode 100644
index 000000000000..af5d60cbbeb1
--- /dev/null
+++ b/apisix/balancer/priority.lua
@@ -0,0 +1,81 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+
+local core = require("apisix.core")
+local ipairs = ipairs
+
+
+local _M = {}
+
+
+local function max_priority(a, b)
+    return a > b
+end
+
+
+function _M.new(up_nodes, upstream, picker_mod)
+    local priority_index = up_nodes._priority_index
+    core.table.sort(priority_index, max_priority)
+
+    local pickers = core.table.new(#priority_index, 0)
+    for i, priority in ipairs(priority_index) do
+        local picker, err = picker_mod.new(up_nodes[priority], upstream)
+        if not picker then
+            return nil, "failed to create picker with priority " .. priority .. ": " .. err
+        end
+        if not picker.before_retry_next_priority then
+            return nil, "picker should define 'before_retry_next_priority' to reset ctx"
+        end
+
+        pickers[i] = picker
+    end
+
+    return {
+        upstream = upstream,
+        get = function (ctx)
+            for i = ctx.priority_balancer_picker_idx or 1, #pickers do
+                local picker = pickers[i]
+                local server, err = picker.get(ctx)
+                if server then
+                    ctx.priority_balancer_picker_idx = i
+                    return server
+                end
+
+                core.log.notice("failed to get server from current priority ",
+                                priority_index[i],
+                                ", try next one, err: ", err)
+
+                picker.before_retry_next_priority(ctx)
+            end
+
+            return nil, "all servers tried"
+        end,
+        after_balance = function (ctx, before_retry)
+            local priority_balancer_picker = pickers[ctx.priority_balancer_picker_idx]
+            if not priority_balancer_picker or
+                not priority_balancer_picker.after_balance
+            then
+                return
+            end
+
+            priority_balancer_picker.after_balance(ctx, before_retry)
+        end
+    }
+end
+
+
+return _M
diff --git a/apisix/balancer/roundrobin.lua b/apisix/balancer/roundrobin.lua
index a9469cac50bb..7090f526117c 100644
--- a/apisix/balancer/roundrobin.lua
+++ b/apisix/balancer/roundrobin.lua
@@ -73,7 +73,15 @@ function _M.new(up_nodes, upstream)
 
             ctx.balancer_tried_servers[ctx.balancer_server] = true
             ctx.balancer_tried_servers_count = (ctx.balancer_tried_servers_count or 0) + 1
-        end
+        end,
+        before_retry_next_priority = function (ctx)
+            if ctx.balancer_tried_servers then
+                core.tablepool.release("balancer_tried_servers", ctx.balancer_tried_servers)
+                ctx.balancer_tried_servers = nil
+            end
+
+            ctx.balancer_tried_servers_count = 0
+        end,
     }
 end
 
diff --git a/apisix/schema_def.lua b/apisix/schema_def.lua
index 9ae7669928ba..57f99150bcb5 100644
--- a/apisix/schema_def.lua
+++ b/apisix/schema_def.lua
@@ -305,6 +305,11 @@ local nodes_schema = {
                         type = "integer",
                         minimum = 0,
                     },
+                    priority = {
+                        description = "priority of node",
+                        type = "integer",
+                        default = 0,
+                    },
                     metadata = {
                         description = "metadata of node",
                         type = "object",
diff --git a/apisix/upstream.lua b/apisix/upstream.lua
index 6ae81c05a4a0..681ce682399d 100644
--- a/apisix/upstream.lua
+++ b/apisix/upstream.lua
@@ -162,6 +162,10 @@ do
 
                 need_filled = true
             end
+
+            if not n.priority then
+                need_filled = true
+            end
         end
 
         up_conf.original_nodes = nodes
@@ -173,9 +177,17 @@ do
 
         local filled_nodes = core.table.new(#nodes, 0)
         for i, n in ipairs(nodes) do
-            if not n.port then
+            if not n.port or not n.priority then
                 filled_nodes[i] = core.table.clone(n)
-                filled_nodes[i].port = scheme_to_port[scheme]
+
+                if not n.port then
+                    filled_nodes[i].port = scheme_to_port[scheme]
+                end
+
+                -- fix priority for non-array nodes and nodes from service discovery
+                if not n.priority then
+                    filled_nodes[i].priority = 0
+                end
             else
                 filled_nodes[i] = n
             end
diff --git a/apisix/utils/upstream.lua b/apisix/utils/upstream.lua
index 2b6077740065..4417f07c1344 100644
--- a/apisix/utils/upstream.lua
+++ b/apisix/utils/upstream.lua
@@ -47,7 +47,7 @@ function _M.compare_upstream_node(up_conf, new_t)
     for i = 1, #new_t do
         local new_node = new_t[i]
         local old_node = old_t[i]
-        for _, name in ipairs({"host", "port", "weight"}) do
+        for _, name in ipairs({"host", "port", "weight", "priority"}) do
             if new_node[name] ~= old_node[name] then
                 return false
             end
diff --git a/docs/en/latest/admin-api.md b/docs/en/latest/admin-api.md
index 51054b90c98f..50158914e74d 100644
--- a/docs/en/latest/admin-api.md
+++ b/docs/en/latest/admin-api.md
@@ -657,6 +657,42 @@ After the execution is successful, nodes will not retain the original data, and
 
 ```
 
+Each node can be configured with a priority. A node with low priority will only be
+used when all the nodes with higher priority are unavailable or tried.
+
+As the default priority is 0, we can configure nodes with negative priority as the backup.
+
+For example,
+
+```json
+{
+    "uri": "/hello",
+    "upstream": {
+        "type": "roundrobin",
+        "nodes": [
+            {"host": "127.0.0.1", "port": 1980, "weight": 2000},
+            {"host": "127.0.0.2", "port": 1980, "weight": 1, "priority": -1}
+        ],
+        "checks": {
+            "active": {
+                "http_path": "/status",
+                "healthy": {
+                    "interval": 1,
+                    "successes": 1
+                },
+                "unhealthy": {
+                    "interval": 1,
+                    "http_failures": 1
+                }
+            }
+        }
+    }
+}
+```
+
+Node `127.0.0.2` will be used only after `127.0.0.1` is unavaibled or tried.
+Therefore it is the backup of `127.0.0.1`.
+
 > Response Parameters
 
 Return response from etcd currently.
diff --git a/docs/en/latest/control-api.md b/docs/en/latest/control-api.md
index 09ee2c9450d0..4efd872fa3df 100644
--- a/docs/en/latest/control-api.md
+++ b/docs/en/latest/control-api.md
@@ -97,6 +97,7 @@ Return current [health check](health-check.md) status in the format below:
             {
                 "host": "127.0.0.1",
                 "port": 1980,
+                "priority": 0,
                 "weight": 1
             }
         ],
@@ -105,11 +106,13 @@ Return current [health check](health-check.md) status in the format below:
             {
                 "host": "127.0.0.1",
                 "port": 1980,
+                "priority": 0,
                 "weight": 1
             },
             {
                 "host": "127.0.0.2",
                 "port": 1988,
+                "priority": 0,
                 "weight": 1
             }
         ],
@@ -121,6 +124,7 @@ Return current [health check](health-check.md) status in the format below:
             {
                 "host": "127.0.0.1",
                 "port": 1980,
+                "priority": 0,
                 "weight": 1
             }
         ],
@@ -129,11 +133,13 @@ Return current [health check](health-check.md) status in the format below:
             {
                 "host": "127.0.0.1",
                 "port": 1980,
+                "priority": 0,
                 "weight": 1
             },
             {
                 "host": "127.0.0.1",
                 "port": 1988,
+                "priority": 0,
                 "weight": 1
             }
         ],
@@ -162,6 +168,7 @@ For example, `GET /v1/healthcheck/upstreams/1` returns:
         {
             "host": "127.0.0.1",
             "port": 1980,
+            "priority": 0,
             "weight": 1
         }
     ],
@@ -170,11 +177,13 @@ For example, `GET /v1/healthcheck/upstreams/1` returns:
         {
             "host": "127.0.0.1",
             "port": 1980,
+            "priority": 0,
             "weight": 1
         },
         {
             "host": "127.0.0.2",
             "port": 1988,
+            "priority": 0,
             "weight": 1
         }
     ],
diff --git a/docs/zh/latest/admin-api.md b/docs/zh/latest/admin-api.md
index eb83d8196ed9..510c7eaf5154 100644
--- a/docs/zh/latest/admin-api.md
+++ b/docs/zh/latest/admin-api.md
@@ -665,6 +665,41 @@ HTTP/1.1 200 OK
 
 ```
 
+节点可以配置自己的优先级。只有在高优先级的节点不可用或者尝试过，才会访问一个低优先级的节点。
+
+由于默认的优先级是 0，我们可以给一些节点配置负数的优先级来作为备份。
+
+举个例子，
+
+```json
+{
+    "uri": "/hello",
+    "upstream": {
+        "type": "roundrobin",
+        "nodes": [
+            {"host": "127.0.0.1", "port": 1980, "weight": 2000},
+            {"host": "127.0.0.2", "port": 1980, "weight": 1, "priority": -1}
+        ],
+        "checks": {
+            "active": {
+                "http_path": "/status",
+                "healthy": {
+                    "interval": 1,
+                    "successes": 1
+                },
+                "unhealthy": {
+                    "interval": 1,
+                    "http_failures": 1
+                }
+            }
+        }
+    }
+}
+```
+
+节点 `127.0.0.2` 只有在 `127.0.0.1` 不可用或者尝试过之后才会被访问。
+所以它是 `127.0.0.1` 的备份。
+
 > 应答参数
 
 目前是直接返回与 etcd 交互后的结果。
diff --git a/t/admin/balancer.t b/t/admin/balancer.t
index d1b9027faad0..9bce5fc8538f 100644
--- a/t/admin/balancer.t
+++ b/t/admin/balancer.t
@@ -70,9 +70,9 @@ __DATA__
             local up_conf = {
                 type = "roundrobin",
                 nodes = {
-                    {host = "39.97.63.215", port = 80, weight = 1},
-                    {host = "39.97.63.216", port = 81, weight = 1},
-                    {host = "39.97.63.217", port = 82, weight = 1},
+                    {host = "39.97.63.215", port = 80, weight = 1, priority = 0},
+                    {host = "39.97.63.216", port = 81, weight = 1, priority = 0},
+                    {host = "39.97.63.217", port = 82, weight = 1, priority = 0},
                 }
             }
             local ctx = {conf_version = 1}
@@ -101,9 +101,9 @@ host: 39.97.63.217 count: 4
             local up_conf = {
                 type = "roundrobin",
                 nodes = {
-                    {host = "39.97.63.215", port = 80, weight = 1},
-                    {host = "39.97.63.216", port = 81, weight = 2},
-                    {host = "39.97.63.217", port = 82, weight = 3},
+                    {host = "39.97.63.215", port = 80, weight = 1, priority = 0},
+                    {host = "39.97.63.216", port = 81, weight = 2, priority = 0},
+                    {host = "39.97.63.217", port = 82, weight = 3, priority = 0},
                 }
             }
             local ctx = {conf_version = 1}
@@ -132,9 +132,9 @@ host: 39.97.63.217 count: 6
             local up_conf = {
                 type = "roundrobin",
                 nodes = {
-                    {host = "39.97.63.215", port = 80, weight = 1},
-                    {host = "39.97.63.216", port = 81, weight = 1},
-                    {host = "39.97.63.217", port = 82, weight = 1},
+                    {host = "39.97.63.215", port = 80, weight = 1, priority = 0},
+                    {host = "39.97.63.216", port = 81, weight = 1, priority = 0},
+                    {host = "39.97.63.217", port = 82, weight = 1, priority = 0},
                 }
             }
             local ctx = {}
@@ -146,8 +146,8 @@ host: 39.97.63.217 count: 6
 
             -- cached by version
             up_conf.nodes = {
-                {host = "39.97.63.218", port = 80, weight = 1},
-                {host = "39.97.63.219", port = 80, weight = 0},
+                {host = "39.97.63.218", port = 80, weight = 1, priority = 0},
+                {host = "39.97.63.219", port = 80, weight = 0, priority = 0},
             }
             test(route, ctx)
 
@@ -179,9 +179,9 @@ host: 39.97.63.218 count: 12
                 type = "chash",
                 key  = "remote_addr",
                 nodes = {
-                    {host = "39.97.63.215", port = 80, weight = 1},
-                    {host = "39.97.63.216", port = 81, weight = 1},
-                    {host = "39.97.63.217", port = 82, weight = 1},
+                    {host = "39.97.63.215", port = 80, weight = 1, priority = 0},
+                    {host = "39.97.63.216", port = 81, weight = 1, priority = 0},
+                    {host = "39.97.63.217", port = 82, weight = 1, priority = 0},
                 }
             }
             local ctx = {
@@ -195,8 +195,8 @@ host: 39.97.63.218 count: 12
 
             -- cached by version
             up_conf.nodes = {
-                {host = "39.97.63.218", port = 80, weight = 1},
-                {host = "39.97.63.219", port = 80, weight = 0},
+                {host = "39.97.63.218", port = 80, weight = 1, priority = 0},
+                {host = "39.97.63.219", port = 80, weight = 0, priority = 0},
             }
             test(route, ctx)
 
@@ -223,9 +223,9 @@ host: 39.97.63.218 count: 12
             local up_conf = {
                 type = "roundrobin",
                 nodes = {
-                    {host = "39.97.63.215", port = 80, weight = 1},
-                    {host = "39.97.63.216", port = 81, weight = 1},
-                    {host = "39.97.63.217", port = 82, weight = 1},
+                    {host = "39.97.63.215", port = 80, weight = 1, priority = 0},
+                    {host = "39.97.63.216", port = 81, weight = 1, priority = 0},
+                    {host = "39.97.63.217", port = 82, weight = 1, priority = 0},
                 }
             }
             local ctx = {}
@@ -237,7 +237,7 @@ host: 39.97.63.218 count: 12
 
             -- one item in nodes, return it directly
             up_conf.nodes = {
-                {host = "39.97.63.218", port = 80, weight = 1},
+                {host = "39.97.63.218", port = 80, weight = 1, priority = 0},
             }
             test(route, ctx)
         }
diff --git a/t/control/healthcheck.t b/t/control/healthcheck.t
index be22420185b3..41fe7f19cf89 100644
--- a/t/control/healthcheck.t
+++ b/t/control/healthcheck.t
@@ -103,8 +103,8 @@ qr/unhealthy TCP increment \(.+\) for '[^']+'/
 unhealthy TCP increment (1/2) for '(127.0.0.2:1988)'
 unhealthy TCP increment (2/2) for '(127.0.0.2:1988)'
 --- response_body
-[{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.2","port":1988,"weight":1}],"src_id":"1","src_type":"upstreams"}]
-{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.2","port":1988,"weight":1}],"src_id":"1","src_type":"upstreams"}
+[{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.2","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"upstreams"}]
+{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.2","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"upstreams"}
 
 
 
@@ -166,8 +166,8 @@ qr/unhealthy TCP increment \(.+\) for '[^']+'/
 unhealthy TCP increment (1/2) for '127.0.0.1(127.0.0.1:1988)'
 unhealthy TCP increment (2/2) for '127.0.0.1(127.0.0.1:1988)'
 --- response_body
-[{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"weight":1}],"name":"upstream#/routes/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.1","port":1988,"weight":1}],"src_id":"1","src_type":"routes"}]
-{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"weight":1}],"name":"upstream#/routes/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.1","port":1988,"weight":1}],"src_id":"1","src_type":"routes"}
+[{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1}],"name":"upstream#/routes/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.1","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"routes"}]
+{"healthy_nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1}],"name":"upstream#/routes/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.1","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"routes"}
 
 
 
@@ -234,8 +234,8 @@ qr/unhealthy TCP increment \(.+\) for '[^']+'/
 unhealthy TCP increment (1/2) for '127.0.0.1(127.0.0.1:1988)'
 unhealthy TCP increment (2/2) for '127.0.0.1(127.0.0.1:1988)'
 --- response_body
-[{"healthy_nodes":{},"name":"upstream#/services/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.1","port":1988,"weight":1}],"src_id":"1","src_type":"services"}]
-{"healthy_nodes":{},"name":"upstream#/services/1","nodes":[{"host":"127.0.0.1","port":1980,"weight":1},{"host":"127.0.0.1","port":1988,"weight":1}],"src_id":"1","src_type":"services"}
+[{"healthy_nodes":{},"name":"upstream#/services/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.1","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"services"}]
+{"healthy_nodes":{},"name":"upstream#/services/1","nodes":[{"host":"127.0.0.1","port":1980,"priority":0,"weight":1},{"host":"127.0.0.1","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"services"}
 
 
 
diff --git a/t/discovery/consul_kv.t b/t/discovery/consul_kv.t
index 3a5e3d6d40a9..30752879c70c 100644
--- a/t/discovery/consul_kv.t
+++ b/t/discovery/consul_kv.t
@@ -461,8 +461,8 @@ upstreams:
 --- request
 GET /thc
 --- response_body
-[{"healthy_nodes":[{"host":"127.0.0.1","port":30511,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":30511,"weight":1},{"host":"127.0.0.2","port":1988,"weight":1}],"src_id":"1","src_type":"upstreams"}]
-{"healthy_nodes":[{"host":"127.0.0.1","port":30511,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":30511,"weight":1},{"host":"127.0.0.2","port":1988,"weight":1}],"src_id":"1","src_type":"upstreams"}
+[{"healthy_nodes":[{"host":"127.0.0.1","port":30511,"priority":0,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":30511,"priority":0,"weight":1},{"host":"127.0.0.2","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"upstreams"}]
+{"healthy_nodes":[{"host":"127.0.0.1","port":30511,"priority":0,"weight":1}],"name":"upstream#/upstreams/1","nodes":[{"host":"127.0.0.1","port":30511,"priority":0,"weight":1},{"host":"127.0.0.2","port":1988,"priority":0,"weight":1}],"src_id":"1","src_type":"upstreams"}
 
 
 
diff --git a/t/node/priority-balancer/health-checker.t b/t/node/priority-balancer/health-checker.t
new file mode 100644
index 000000000000..445210bd6caf
--- /dev/null
+++ b/t/node/priority-balancer/health-checker.t
@@ -0,0 +1,187 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+repeat_each(1);
+log_level('info');
+no_root_location();
+worker_connections(1024);
+no_shuffle();
+
+add_block_preprocessor(sub {
+    my ($block) = @_;
+
+    if ($block->apisix_yaml) {
+        if (!$block->yaml_config) {
+            my $yaml_config = <<_EOC_;
+apisix:
+    node_listen: 1984
+    config_center: yaml
+    enable_admin: false
+_EOC_
+
+            $block->set_value("yaml_config", $yaml_config);
+        }
+
+        my $route = <<_EOC_;
+routes:
+    -
+    upstream_id: 1
+    uris:
+        - /hello
+#END
+_EOC_
+
+        $block->set_value("apisix_yaml", $block->apisix_yaml . $route);
+    }
+
+    if (!$block->request) {
+        $block->set_value("request", "GET /hello");
+    }
+
+    if ((!defined $block->error_log) && (!defined $block->no_error_log)) {
+        $block->set_value("no_error_log", "[error]");
+    }
+});
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: all are down detected by health checker
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: least_conn
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 123
+        - host: 127.0.0.2
+          port: 1979
+          weight: 3
+          priority: -1
+    checks:
+        active:
+            http_path: "/status"
+            healthy:
+                interval: 1
+                successes: 1
+            unhealthy:
+                interval: 1
+                http_failures: 1
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port
+                        .. "/hello"
+            local httpc = http.new()
+            httpc:request_uri(uri, {method = "GET"})
+            ngx.sleep(2.5)
+            -- still use all nodes
+            httpc:request_uri(uri, {method = "GET"})
+        }
+    }
+--- request
+GET /t
+--- error_log
+connect() failed
+unhealthy TCP increment (2/2) for '(127.0.0.1:1979)
+unhealthy TCP increment (2/2) for '(127.0.0.2:1979)
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+
+
+
+=== TEST 2: use priority as backup (setup rule)
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/routes/1',
+                 ngx.HTTP_PUT,
+                 [[{
+                        "uri": "/hello",
+                        "upstream": {
+                            "type": "roundrobin",
+                            "nodes": [
+                                {"host": "127.0.0.1", "port": 1979, "weight": 2000},
+                                {"host": "127.0.0.1", "port": 1980,
+                                 "weight": 1, "priority": -1}
+                            ],
+                            "checks": {
+                                "active": {
+                                    "http_path": "/status",
+                                    "healthy": {
+                                        "interval": 1,
+                                        "successes": 1
+                                    },
+                                    "unhealthy": {
+                                        "interval": 1,
+                                        "http_failures": 1
+                                    }
+                                }
+                            }
+                        }
+                }]]
+                )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+
+
+
+=== TEST 3: use priority as backup
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port
+                        .. "/hello"
+            local httpc = http.new()
+            httpc:request_uri(uri, {method = "GET"})
+            ngx.sleep(2.5)
+            httpc:request_uri(uri, {method = "GET"})
+        }
+    }
+--- request
+GET /t
+--- error_log
+connect() failed
+unhealthy TCP increment (2/2) for '(127.0.0.1:1979)
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.1:1980
+proxy request to 127.0.0.1:1980
diff --git a/t/node/priority-balancer/sanity.t b/t/node/priority-balancer/sanity.t
new file mode 100644
index 000000000000..aeb9735343fd
--- /dev/null
+++ b/t/node/priority-balancer/sanity.t
@@ -0,0 +1,332 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+repeat_each(2); # repeat each test to ensure after_balance is called correctly
+log_level('info');
+no_root_location();
+worker_connections(1024);
+no_shuffle();
+
+add_block_preprocessor(sub {
+    my ($block) = @_;
+
+    if ($block->apisix_yaml) {
+        if (!$block->yaml_config) {
+            my $yaml_config = <<_EOC_;
+apisix:
+    node_listen: 1984
+    config_center: yaml
+    enable_admin: false
+_EOC_
+
+            $block->set_value("yaml_config", $yaml_config);
+        }
+
+        my $route = <<_EOC_;
+routes:
+    -
+    upstream_id: 1
+    uris:
+        - /hello
+        - /mysleep
+#END
+_EOC_
+
+        $block->set_value("apisix_yaml", $block->apisix_yaml . $route);
+    }
+
+    if (!$block->request) {
+        $block->set_value("request", "GET /hello");
+    }
+
+    if ((!defined $block->error_log) && (!defined $block->no_error_log)) {
+        $block->set_value("no_error_log", "[error]");
+    }
+});
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: sanity
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: least_conn
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+          priority: 1
+        - host: 127.0.0.3
+          port: 1979
+          weight: 2
+          priority: 0
+        - host: 127.0.0.4
+          port: 1979
+          weight: 1
+          priority: 0
+        - host: 127.0.0.1
+          port: 1980
+          weight: 2
+          priority: -1
+--- response_body
+hello world
+--- error_log
+connect() failed
+failed to get server from current priority 1, try next one
+failed to get server from current priority 0, try next one
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.3:1979
+proxy request to 127.0.0.4:1979
+proxy request to 127.0.0.1:1980
+
+
+
+=== TEST 2: all failed
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: least_conn
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+          priority: 0
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: -1
+--- error_code: 502
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.1:1979
+
+
+
+=== TEST 3: default priority is zero
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: least_conn
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+        - host: 127.0.0.1
+          port: 1980
+          weight: 2
+          priority: -1
+--- response_body
+hello world
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.1:1980
+
+
+
+=== TEST 4: least_conn
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: least_conn
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.1
+          port: 1980
+          weight: 3
+          priority: -1
+        - host: 0.0.0.0
+          port: 1980
+          weight: 2
+          priority: -1
+--- config
+    location /t {
+        content_by_lua_block {
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port
+                        .. "/mysleep?seconds=0.1"
+
+            local t = {}
+            for i = 1, 3 do
+                local th = assert(ngx.thread.spawn(function(i)
+                    local httpc = http.new()
+                    local res, err = httpc:request_uri(uri..i, {method = "GET"})
+                    if not res then
+                        ngx.log(ngx.ERR, err)
+                        return
+                    end
+                end, i))
+                table.insert(t, th)
+            end
+            for i, th in ipairs(t) do
+                ngx.thread.wait(th)
+            end
+        }
+    }
+--- request
+GET /t
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+ while connecting to upstream/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979 while connecting to upstream
+proxy request to 127.0.0.1:1979 while connecting to upstream
+proxy request to 127.0.0.1:1979 while connecting to upstream
+proxy request to 127.0.0.1:1980 while connecting to upstream
+proxy request to 0.0.0.0:1980 while connecting to upstream
+proxy request to 127.0.0.1:1980 while connecting to upstream
+
+
+
+=== TEST 5: roundrobin
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: roundrobin
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+          priority: 1
+        - host: 127.0.0.3
+          port: 1979
+          weight: 2
+          priority: -1
+        - host: 127.0.0.4
+          port: 1979
+          weight: 1
+          priority: -1
+--- error_code: 502
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.3:1979
+proxy request to 127.0.0.4:1979
+
+
+
+=== TEST 6: ewma
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: ewma
+    key: remote_addr
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+          priority: 0
+        - host: 127.0.0.3
+          port: 1979
+          weight: 2
+          priority: -1
+--- error_code: 502
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.3:1979
+
+
+
+=== TEST 7: chash
+--- apisix_yaml
+upstreams:
+    -
+    id: 1
+    type: chash
+    key: remote_addr
+    nodes:
+        - host: 127.0.0.1
+          port: 1979
+          weight: 2
+          priority: 1
+        - host: 127.0.0.2
+          port: 1979
+          weight: 1
+          priority: 1
+        - host: 127.0.0.3
+          port: 1979
+          weight: 2
+          priority: -1
+        - host: 127.0.0.4
+          port: 1979
+          weight: 1
+          priority: -1
+--- error_code: 502
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 127.0.0.2:1979
+proxy request to 127.0.0.4:1979
+proxy request to 127.0.0.3:1979
diff --git a/t/node/upstream-discovery.t b/t/node/upstream-discovery.t
index eba81514248c..6b51d7c5095f 100644
--- a/t/node/upstream-discovery.t
+++ b/t/node/upstream-discovery.t
@@ -230,7 +230,6 @@ routes:
             local httpc = http.new()
             local res, err = httpc:request_uri(uri, {method = "GET", keepalive = false})
             ngx.say(res.status)
-
             discovery.mock = {
                 nodes = function()
                     return {
@@ -250,3 +249,86 @@ qr/create_obj_fun\(\): upstream nodes:/
 create_obj_fun(): upstream nodes:
 --- error_log
 connect() failed
+
+
+
+=== TEST 5: create new server picker when priority change
+--- apisix_yaml
+routes:
+  -
+    uris:
+        - /hello
+    upstream_id: 1
+--- config
+    location /t {
+        content_by_lua_block {
+            local discovery = require("apisix.discovery.init").discovery
+            discovery.mock = {
+                nodes = function()
+                    return {
+                        {host = "127.0.0.1", port = 1980, weight = 1},
+                        {host = "0.0.0.0", port = 1980, weight = 1},
+                    }
+                end
+            }
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            local httpc = http.new()
+            local res, err = httpc:request_uri(uri, {method = "GET", keepalive = false})
+            ngx.say(res.status)
+
+            discovery.mock = {
+                nodes = function()
+                    return {
+                        {host = "127.0.0.1", port = 1980, weight = 1},
+                        {host = "0.0.0.0", port = 1980, weight = 1, priority = 1},
+                    }
+                end
+            }
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            local httpc = http.new()
+            local res, err = httpc:request_uri(uri, {method = "GET", keepalive = false})
+        }
+    }
+--- grep_error_log eval
+qr/create_obj_fun\(\): upstream nodes:/
+--- grep_error_log_out
+create_obj_fun(): upstream nodes:
+create_obj_fun(): upstream nodes:
+
+
+
+=== TEST 6: default priority of discovered node is 0
+--- apisix_yaml
+routes:
+  -
+    uris:
+        - /hello
+    upstream_id: 1
+--- config
+    location /t {
+        content_by_lua_block {
+            local discovery = require("apisix.discovery.init").discovery
+            discovery.mock = {
+                nodes = function()
+                    return {
+                        {host = "127.0.0.1", port = 1979, weight = 1, priority = 1},
+                        {host = "0.0.0.0", port = 1980, weight = 1},
+                        {host = "127.0.0.2", port = 1979, weight = 1, priority = -1},
+                    }
+                end
+            }
+            local http = require "resty.http"
+            local uri = "http://127.0.0.1:" .. ngx.var.server_port .. "/hello"
+            local httpc = http.new()
+            local res, err = httpc:request_uri(uri, {method = "GET", keepalive = false})
+            ngx.say(res.status)
+        }
+    }
+--- error_log
+connect() failed
+--- grep_error_log eval
+qr/proxy request to \S+/
+--- grep_error_log_out
+proxy request to 127.0.0.1:1979
+proxy request to 0.0.0.0:1980