diff --git a/lib/mm.js b/lib/mm.js
index 1f6aeee..acc5580 100644
--- a/lib/mm.js
+++ b/lib/mm.js
@@ -14,7 +14,8 @@ var EventEmitter = require('events').EventEmitter;
 var muk = require('muk');
 var http = require('http');
 var https = require('https');
-
+var cp = require('child_process');
+var EventEmitter = require('events').EventEmitter;
 
 exports = module.exports = function mock(obj, key, method) {
   return muk.apply(null, arguments);
@@ -305,6 +306,25 @@ function _requestError(mod, url, reqError, resError, delay) {
   return this;
 }
 
+/**
+ * mock child_process spawn
+ * @param {Integer} code exit code
+ * @param {String} stdout 
+ * @param {String} stderr 
+ * @param {Integer} timeout stdout/stderr/close event emit timeout
+ */
+exports.spawn = function (code, stdout, stderr, timeout) {
+  var evt = new EventEmitter();
+  muk(cp, 'spawn', function () {
+    return evt;
+  });
+  setTimeout(function () {
+    stdout && evt.emit('stdout', stdout);
+    stderr && evt.emit('stderr', stderr);
+    evt.emit('close', code);
+  }, timeout);  
+};
+
 /**
  * remove all mock effects.
  */
diff --git a/test/mm.test.js b/test/mm.test.js
index 67dd568..915caac 100644
--- a/test/mm.test.js
+++ b/test/mm.test.js
@@ -16,10 +16,10 @@ var fs = require('fs');
 var should = require('should');
 var http = require('http');
 var https = require('https');
+var child_process = require('child_process');
 var pedding = require('pedding');
 var foo = require('./foo');
 
-
 describe('mm.test.js', function () {
 
   var port = null;
@@ -524,6 +524,32 @@ describe('mm.test.js', function () {
 
   });
 
+  describe('spawn', function () {
+    it('should mm.spawn mock spawn', function (done) {
+      mm.spawn(1, 'stdout', 'stderr', 100);
+      var ls = child_process.spawn('ls', ['-a']);
+      var done = pedding(4, done);
+      ls.on('stdout', function (data) {
+        data.should.equal('stdout');
+        done();
+      });
+      ls.on('stderr', function (data) {
+        data.should.equal('stderr');
+        done();
+      });      
+      ls.on('close', function (code) {
+        code.should.equal(1);
+        done();
+      });
+      mm.restore();
+      var ls = child_process.spawn('ls', ['-a']);
+      ls.on('close', function (code) {
+        code.should.equal(0);
+        done();
+      });
+    });
+  });
+
   describe('mm()', function () {
     it('should mm() just like muk()', function (done) {
       mm(fs, 'readFile', function (filename, callback) {