diff --git a/README.md b/README.md
index 99cb4c1..977c7c3 100644
--- a/README.md
+++ b/README.md
@@ -34,6 +34,7 @@ $ npm install parameter --save
   - `options.translate` - translate function
   - `options.validateRoot` - config whether to validate the passed in value must be a object, default to `false`.
   - `options.convert` - convert primitive params to specific type, default to `false`.
+  - `optinos.widelyUndefined` - convert empty string(`''`), NaN, Null to undefined, this option can make `rule.required` more powerful, default to `false`.__This may change the original input params__.
 - `validate(rule, value)` - validate the `value` conforms to `rule`. return an array of errors if break rule.
 - `addRule(type, check)` - add custom rules.
    - `type` - rule type, required and must be string type.
@@ -79,6 +80,7 @@ var errors = parameter.validate(rule, data);
 - `required` - if `required` is set to false, this property can be null or undefined. default to `true`.
 - `type` - The type of property, every type has it's own rule for the validate.
 - `convertType` - Make parameter convert the input param to the specific type, support `int`, `number`, `string` and `boolean`, also support a function to customize your own convert method.
+- `default` - The default value of property, once the property is allowed non-required and missed, parameter will use this as the default value. __This may change the original input params__.
 
 __Note: you can combile require and type end with a notation `?` like: `int?` or `string?` to specific both type and non-required.__
 
diff --git a/index.js b/index.js
index 0ccfb82..b2f83d3 100644
--- a/index.js
+++ b/index.js
@@ -32,6 +32,7 @@ class Parameter {
 
     if (opts.validateRoot) this.validateRoot = true;
     if (opts.convert) this.convert = true;
+    if (opts.widelyUndefined) this.widelyUndefined = true;
   }
 
   t() {
@@ -70,6 +71,13 @@ class Parameter {
     for (var key in rules) {
       var rule = formatRule(rules[key]);
       var value = obj[key];
+
+      // treat null / '' / NaN as undefined
+      if (this.widelyUndefined &&
+        (value === '' || value === null || Number.isNaN(value))) {
+        value = obj[key] = undefined;
+      }
+
       var has = value !== null && value !== undefined;
 
       if (!has) {
@@ -80,6 +88,10 @@ class Parameter {
             code: this.t('missing_field')
           });
         }
+        // support default value
+        if (rule.default) {
+          obj[key] = rule.default;
+        }
         continue;
       }
 
diff --git a/test/index.test.js b/test/index.test.js
index bcdae50..99c98e0 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -13,6 +13,10 @@ var parameterWithConvert = new Parameter({
   convert: true,
 });
 
+var parameterWithWidelyUndefined = new Parameter({
+  widelyUndefined: true,
+});
+
 describe('parameter', function () {
   describe('required', function () {
     it('should required work fine', function () {
@@ -1015,4 +1019,81 @@ describe('validate with options.convert', function() {
     should.not.exist(res);
     value.int.should.equal(1);
   });
+
+  describe('validate with options.widelyUndefined', function () {
+    it('should convert null / NaN / "" to undefiend', function() {
+      var value = {
+        number: NaN,
+        string: '',
+        date: null,
+        foo: 'test string',
+        bar: 123,
+      };
+      var res = parameterWithWidelyUndefined.validate({
+        number: 'number?',
+        string: 'string?',
+        date: 'date?',
+        foo: 'string',
+        bar: 'int',
+      }, value);
+      should.not.exist(res);
+      value.should.eql({
+        number: undefined,
+        string: undefined,
+        date: undefined,
+        foo: 'test string',
+        bar: 123,
+      });
+    });
+  });
+
+  describe('default', function() {
+    it('should default work', function () {
+      var value = {
+        string: '',
+        foo: null,
+        bar: 123,
+      };
+      var res = parameter.validate({
+        string: { type: 'string?', default: 'string' },
+        foo: { type: 'string?', default: 'foo' },
+        bar: { type: 'int?', default: 1200 },
+        hello: { type: 'string?', default: 'world' },
+      }, value);
+      should.not.exist(res);
+      value.should.eql({
+        string: '', // notice: string '' is not undefined here
+        foo: 'foo',
+        bar: 123,
+        hello: 'world',
+      });
+    });
+
+    it('should default work with widelyUndefined', function() {
+      var value = {
+        number: NaN,
+        string: '',
+        date: null,
+        foo: 'test string',
+        bar: 123,
+      };
+      var res = parameterWithWidelyUndefined.validate({
+        number: { type: 'number?', default: 100 },
+        string: { type: 'string?', default: 'string' },
+        date: { type: 'date?', default: 100 },
+        foo: { type: 'string?', default: 'foo' },
+        bar: { type: 'int?', default: 1200 },
+        hello: { type: 'string?', default: 'world' },
+      }, value);
+      should.not.exist(res);
+      value.should.eql({
+        number: 100,
+        string: 'string',
+        date: 100,
+        foo: 'test string',
+        bar: 123,
+        hello: 'world',
+      });
+    });
+  });
 });