diff --git a/components/button/button-group.jsx b/components/button/button-group.jsx
index 7de6bea230..d4c94effca 100644
--- a/components/button/button-group.jsx
+++ b/components/button/button-group.jsx
@@ -1,20 +1,18 @@
 import React from 'react';
+import rcUtil from 'rc-util';
 
 const prefix = 'ant-btn-group-';
 
 export default class ButtonGroup extends React.Component {
   render() {
     const {size, className, ...others} = this.props;
+    const classes = rcUtil.classSet({
+      'ant-btn-group': true,
+      [prefix + size]: size,
+      [className]: className
+    });
 
-    let classSet = ['ant-btn-group'];
-    if (size) {
-      classSet.push(prefix + size);
-    }
-    if (className) {
-      classSet.push(className);
-    }
-
-    return <div {...others} className={classSet.join(' ')} />;
+    return <div {...others} className={classes} />;
   }
 }
 ButtonGroup.propTypes = {
diff --git a/components/button/button.jsx b/components/button/button.jsx
index 7cef8ece7a..b6f49083c9 100644
--- a/components/button/button.jsx
+++ b/components/button/button.jsx
@@ -1,4 +1,5 @@
 import React from 'react';
+import rcUtil from 'rc-util';
 
 const rxTwoCNChar = /^[\u4e00-\u9fa5]{2,2}$/;
 const isTwoCNChar = rxTwoCNChar.test.bind(rxTwoCNChar);
@@ -7,11 +8,6 @@ function isString(str) {
 }
 
 const prefix = 'ant-btn-';
-function updateClassWithProp(classSet, prop) {
-  if (prop) {
-    classSet.push(prefix + prop);
-  }
-}
 
 // Insert one space between two chinese characters automatically.
 function insertSpace(child) {
@@ -32,20 +28,18 @@ export default class Button extends React.Component {
     const props = this.props;
     const {type, shape, size, onClick, className, children, ...others} = props;
 
-    let classSet = ['ant-btn'];
-    updateClassWithProp(classSet, type);
-    updateClassWithProp(classSet, shape);
-    updateClassWithProp(classSet, size);
-    if ('loading' in props && props.loading !== false) {
-      classSet.push(prefix + 'loading');
-    }
-    if (className) {
-      classSet.push(className);
-    }
+    const classes = rcUtil.classSet({
+      'ant-btn': true,
+      [prefix + type]: type,
+      [prefix + shape]: shape,
+      [prefix + size]: size,
+      [prefix + 'loading']: ('loading' in props && props.loading !== false),
+      [className]: className
+    });
 
     const kids = React.Children.map(children, insertSpace);
 
-    return <button {...others} type="button" className={classSet.join(' ')} onClick={onClick}>
+    return <button {...others} type="button" className={classes} onClick={onClick}>
       {kids}
     </button>;
   }