<body>
<script language="javascript" type="text/javascript">
var pros =new Array(); //定义省的数组
pros[0]="辽宁省";
pros[1]="吉林省";
var citys = new Array(); //定义市的数组
citys[0]= new Array();
citys[1]= new Array();
citys[0][0]="沈阳市";
citys[0][1]="大连市";
citys[1][0]="长春市";
citys[1][1]="吉林市";
function changeCity(){
var city=document.getElementById("city");
var province=document.getElementById("province");
city.options.length=0;
var pvalue=province.options[province.selectedIndex].value; //？希望大神指教，我也不是很懂。。
for (var i=0;i<citys[pvalue].length;i++){
var text=citys[pvalue][i];
var value=i;
city.options[city.options.length]=new Option(text,value);
}
}
</script>
省份：<select name="province" id="province" onchange="changeCity()">
<option value="x">请选择省份</option>
<script language="javascript" type="text/javascript">
for (var i=0;i<pros.length;i++){
document.write("<option value='"+i+"'>"+pros[i]+"</option>");
}
</script>
</select>
城市：<select name="city" id="city" >
<option value="0">请选择城市</option>
</select>
<br/>
</body>