自己写的，未使用jquery.select.js下的功能，只是用了jquery本身
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script language="javascript" src="jquery.js"></script>
<script language="javascript">
function chengequyu(){
var qu = $("#qu").val();
switch(qu){
case "01":
$("#quyu").empty();
$("<option value='01'>复兴门商圈</option><option value='02'>宣武门商圈</option><option value='03'>和平门商圈</option>").appendTo("#quyu");
break;
case "02":
$("#quyu").empty();
$("<option value='04'>崇文门商圈</option><option value='05'>北京站商圈</option><option value='06'>方庄商圈</option>").appendTo("#quyu");
break;
case "03":
$("#quyu").empty();
$("<option value='07'>万达商圈</option><option value='08'>双井商圈</option><option value='09'>SOHO商圈</option>").appendTo("#quyu");
break;
}
}
</script>
</head>
<body>
<select name="qu" id="qu" οnchange="chengequyu()">
<option value="01" SELECTED>宣武区</option>
<option value="02">崇文区</option>
<option value="03">朝阳区</option>
</select>
<SELECT NAME="quyu" id="quyu">
<OPTION VALUE="01" SELECTED>复兴门商圈</OPTION>
<OPTION VALUE="02">宣武门商圈</OPTION>
<OPTION VALUE="03">和平门商圈</OPTION>
</SELECT>
</body>
</html>
