给你个简单的例子:
<html><head>
<meta http-equiv="Content-Language" content="zh-cn">
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<meta name="GENERATOR" content="Microsoft FrontPage 4.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title>Radio's Value</title>
</head>
<body>
<form method="POST" action="--WEBBOT-SELF--">
  <input type="radio" value="V1" name="R1"  onclick="document.all.radiovalue.value=this.value;">a    
  <input type="radio" value="V2" checked name="R1"   onclick="document.all.radiovalue.value=this.value;">b    
  <input type="button" value="提交" name="B1" onclick="alert(document.all.radiovalue.value);">
  <input type="hidden" value="" name=radiovalue>  
</form>
</body>
</html>