diff --git a/components/input-number/index.jsx b/components/input-number/index.jsx
index ad14782ea6..c9d919698b 100644
--- a/components/input-number/index.jsx
+++ b/components/input-number/index.jsx
@@ -1,5 +1,6 @@
-import InputNumber from 'rc-input-number';
 import React from 'react';
+import classNames from 'classnames';
+import InputNumber from 'rc-input-number';
 
 export default React.createClass({
   getDefaultProps() {
@@ -9,12 +10,13 @@ export default React.createClass({
     };
   },
   render() {
-    let sizeClass = '';
-    if (this.props.size === 'large') {
-      sizeClass = 'ant-input-number-lg';
-    } else if (this.props.size === 'small') {
-      sizeClass = 'ant-input-number-sm';
-    }
-    return <InputNumber className={sizeClass} {...this.props} />;
+    const {className, size, ...other} = this.props;
+    const inputNumberClass = classNames({
+      'ant-input-number-lg': size === 'large',
+      'ant-input-number-sm': size === 'small',
+      [className]: !!className,
+    });
+
+    return <InputNumber className={inputNumberClass} {...other} />;
   }
 });