diff --git a/Readme.md b/Readme.md
index 8ea2bb9..27730c7 100644
--- a/Readme.md
+++ b/Readme.md
@@ -196,6 +196,17 @@ fn(true).then(function (val) {
 });
 ```
 
+### co.setPromise(Promise)
+
+You can custom `Promise` that you like . Such as `bluebird`, `q`, `when` and so on.
+
+```js
+var Promise = require('bluebird');
+co.promise = Promise;
+
+co(11).tap(console.log);
+```
+
 ## License
 
   MIT
diff --git a/index.js b/index.js
index aacf6ef..8ab19d0 100644
--- a/index.js
+++ b/index.js
@@ -5,12 +5,31 @@
 
 var slice = Array.prototype.slice;
 
+/**
+ * default Promise
+ */
+
+var Promise = global.Promise;
+
 /**
  * Expose `co`.
  */
 
 module.exports = co['default'] = co.co = co;
 
+/**
+ * custom your Promise that you like
+ */
+
+Object.defineProperty(co,"promise",{
+  get: function () {
+    return Promise;
+  },
+  set: function (promise) {
+    Promise = promise;
+  }
+});
+
 /**
  * Wrap the given generator `fn` into a
  * function that returns a promise.