<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style type="text/css">
.message{
width:200px;
height:100px;
background-color:#CCC;}
</style>
</head>
<body>
<script type="text/javascript">
var element=document.createElement("p");
element.className="message";
var a=document.createTextNode("I love JavaScript!");
document.body.appendChild(element);
element.innerHTML=a;
</script>
</body>
</html>你既然用了document.createTextNode()，就应该用element.appendChild()赋值，就错在element.innerHTML=a，改成：element.appendChild(a);就行了