diff --git a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvoker.java b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
index 2e3ab143a4d..090f2862e67 100644
--- a/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
+++ b/dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvoker.java
@@ -22,6 +22,7 @@
 import org.apache.dubbo.common.extension.ExtensionLoader;
 import org.apache.dubbo.common.logger.Logger;
 import org.apache.dubbo.common.logger.LoggerFactory;
+import org.apache.dubbo.common.utils.CollectionUtils;
 import org.apache.dubbo.common.utils.NetUtils;
 import org.apache.dubbo.rpc.Invocation;
 import org.apache.dubbo.rpc.Invoker;
@@ -94,17 +95,18 @@ public void destroy() {
 
     /**
      * Select a invoker using loadbalance policy.</br>
-     * a)Firstly, select an invoker using loadbalance. If this invoker is in previously selected list, or,
+     * a) Firstly, select an invoker using loadbalance. If this invoker is in previously selected list, or,
      * if this invoker is unavailable, then continue step b (reselect), otherwise return the first selected invoker</br>
-     * b)Reslection, the validation rule for reselection: selected > available. This rule guarantees that
+     * <p>
+     * b) Reslection, the validation rule for reselection: selected > available. This rule guarantees that
      * the selected invoker has the minimum chance to be one in the previously selected list, and also
      * guarantees this invoker is available.
      *
      * @param loadbalance load balance policy
-     * @param invocation
-     * @param invokers invoker candidates
-     * @param selected  exclude selected invokers or not
-     * @return
+     * @param invocation  invocation
+     * @param invokers    invoker candidates
+     * @param selected    exclude selected invokers or not
+     * @return the invoker which will final to do invoke.
      * @throws RpcException
      */
     protected Invoker<T> select(LoadBalance loadbalance, Invocation invocation, List<Invoker<T>> invokers, List<Invoker<T>> selected) throws RpcException {
@@ -138,9 +140,6 @@ private Invoker<T> doSelect(LoadBalance loadbalance, Invocation invocation, List
             return null;
         if (invokers.size() == 1)
             return invokers.get(0);
-        if (loadbalance == null) {
-            loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE);
-        }
         Invoker<T> invoker = loadbalance.select(invokers, getUrl(), invocation);
 
         //If the `invoker` is in the  `selected` or invoker is unavailable && availablecheck is true, reselect.
@@ -226,7 +225,6 @@ private Invoker<T> reselect(LoadBalance loadbalance, Invocation invocation,
     @Override
     public Result invoke(final Invocation invocation) throws RpcException {
         checkWhetherDestroyed();
-        LoadBalance loadbalance = null;
 
         // binding attachments into invocation.
         Map<String, String> contextAttachments = RpcContext.getContext().getAttachments();
@@ -235,10 +233,7 @@ public Result invoke(final Invocation invocation) throws RpcException {
         }
 
         List<Invoker<T>> invokers = list(invocation);
-        if (invokers != null && !invokers.isEmpty()) {
-            loadbalance = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
-                    .getMethodParameter(RpcUtils.getMethodName(invocation), Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
-        }
+        LoadBalance loadbalance = initLoadBalance(invokers, invocation);
         RpcUtils.attachInvocationIdIfAsync(getUrl(), invocation);
         return doInvoke(invocation, invokers, loadbalance);
     }
@@ -276,4 +271,24 @@ protected List<Invoker<T>> list(Invocation invocation) throws RpcException {
         List<Invoker<T>> invokers = directory.list(invocation);
         return invokers;
     }
+
+    /**
+     * Init LoadBalance.
+     * <p>
+     * if invokers is not empty, init from the first invoke's url and invocation
+     * if invokes is empty, init a default LoadBalance(RandomLoadBalance)
+     * </p>
+     *
+     * @param invokers   invokers
+     * @param invocation invocation
+     * @return LoadBalance instance. if not need init, return null.
+     */
+    protected LoadBalance initLoadBalance(List<Invoker<T>> invokers, Invocation invocation) {
+        if (CollectionUtils.isNotEmpty(invokers)) {
+            return ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(invokers.get(0).getUrl()
+                    .getMethodParameter(RpcUtils.getMethodName(invocation), Constants.LOADBALANCE_KEY, Constants.DEFAULT_LOADBALANCE));
+        } else {
+            return ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(Constants.DEFAULT_LOADBALANCE);
+        }
+    }
 }
diff --git a/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvokerTest.java b/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvokerTest.java
index c249131227e..247a719ad84 100644
--- a/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvokerTest.java
+++ b/dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/support/AbstractClusterInvokerTest.java
@@ -51,7 +51,6 @@
 
 /**
  * AbstractClusterInvokerTest
- *
  */
 @SuppressWarnings("rawtypes")
 public class AbstractClusterInvokerTest {
@@ -161,14 +160,16 @@ protected Result doInvoke(Invocation invocation, List invokers, LoadBalance load
 
     @Test
     public void testSelect_Invokersize0() throws Exception {
+        LoadBalance l = cluster.initLoadBalance(invokers, invocation);
+        Assert.assertNotNull("cluster.initLoadBalance returns null!", l);
         {
-            Invoker invoker = cluster.select(null, null, null, null);
+            Invoker invoker = cluster.select(l, null, null, null);
             Assert.assertEquals(null, invoker);
         }
         {
             invokers.clear();
             selectedInvokers.clear();
-            Invoker invoker = cluster.select(null, null, invokers, null);
+            Invoker invoker = cluster.select(l, null, invokers, null);
             Assert.assertEquals(null, invoker);
         }
     }
@@ -177,7 +178,9 @@ public void testSelect_Invokersize0() throws Exception {
     public void testSelect_Invokersize1() throws Exception {
         invokers.clear();
         invokers.add(invoker1);
-        Invoker invoker = cluster.select(null, null, invokers, null);
+        LoadBalance l = cluster.initLoadBalance(invokers, invocation);
+        Assert.assertNotNull("cluster.initLoadBalance returns null!", l);
+        Invoker invoker = cluster.select(l, null, invokers, null);
         Assert.assertEquals(invoker1, invoker);
     }
 
@@ -186,16 +189,18 @@ public void testSelect_Invokersize2AndselectNotNull() throws Exception {
         invokers.clear();
         invokers.add(invoker2);
         invokers.add(invoker4);
+        LoadBalance l = cluster.initLoadBalance(invokers, invocation);
+        Assert.assertNotNull("cluster.initLoadBalance returns null!", l);
         {
             selectedInvokers.clear();
             selectedInvokers.add(invoker4);
-            Invoker invoker = cluster.select(null, invocation, invokers, selectedInvokers);
+            Invoker invoker = cluster.select(l, invocation, invokers, selectedInvokers);
             Assert.assertEquals(invoker2, invoker);
         }
         {
             selectedInvokers.clear();
             selectedInvokers.add(invoker2);
-            Invoker invoker = cluster.select(null, invocation, invokers, selectedInvokers);
+            Invoker invoker = cluster.select(l, invocation, invokers, selectedInvokers);
             Assert.assertEquals(invoker4, invoker);
         }
     }