html和js部分
<!DOCTYPE html>
<html>
<head>
<meta charset=gbk />
<title>selectList</title>
<style type="text/css">
*{margin:0;padding:0;}
.selectList{width:200px;margin:50px auto;}
</style>
<script type="text/javascript" src="jquery1.7.1.js"></script>
</head>
<body>
<div class="selectList">
<select class="province">
<option>请选择</option>
</select>
<select class="city">
<option>请选择</option>
</select>
<select class="district">
<option>请选择</option>
</select>
</div>
<div class="selectList">
<select class="province">
<option>请选择</option>
</select>
<select class="city">
<option>请选择</option>
</select>
<select class="district">
<option>请选择</option>
</select>
</div>
<script type="text/javascript">
$(function(){
$(".selectList").each(function(){
var url = "area.json";
var areaJson;
var temp_html;
var oProvince = $(this).find(".province");
var oCity = $(this).find(".city");
var oDistrict = $(this).find(".district");
//初始化省
var province = function(){
$.each(areaJson,function(i,province){
temp_html+="<option value='"+province.p+"'>"+province.p+"</option>";
});
oProvince.html(temp_html);
city();
};
//赋值市
var city = function(){
temp_html = "";
var n = oProvince.get(0).selectedIndex;
$.each(areaJson[n].c,function(i,city){
temp_html+="<option value='"+city.ct+"'>"+city.ct+"</option>";
});
oCity.html(temp_html);
district();
};
//赋值县
var district = function(){
temp_html = "";
var m = oProvince.get(0).selectedIndex;
var n = oCity.get(0).selectedIndex;
if(typeof(areaJson[m].c[n].d) == "undefined"){
oDistrict.css("display","none");
}else{
oDistrict.css("display","inline");
$.each(areaJson[m].c[n].d,function(i,district){
temp_html+="<option value='"+district.dt+"'>"+district.dt+"</option>";
});
oDistrict.html(temp_html);
};
};
//选择省改变市
oProvince.change(function(){
city();
});
//选择市改变县
oCity.change(function(){
district();
});
//获取json数据
$.getJSON(url,function(data){
areaJson = data;
province();
});
});
});
</script>
</body>
</html>
json文件（area.json），这里只是事例，根据情况添加或编写
[
{"p":"江西省",
"c":[
{"ct":"南昌市",
"d":[
{"dt":"西湖区"},
{"dt":"东湖区"},
{"dt":"高新区"}
]},
{"ct":"赣州市",
"d":[
{"dt":"瑞金县"},
{"dt":"南丰县"},
{"dt":"全南县"}
]}
]},
{"p":"北京",
"c":[
{"ct":"东城区"},
{"ct":"西城区"}
]},
{"p":"河北省",
"c":[
{"ct":"石家庄",
"d":[
{"dt":"长安区"},
{"dt":"桥东区"},
{"dt":"桥西区"}
]},
{"ct":"唐山市",
"d":[
{"dt":"滦南县"},
{"dt":"乐亭县"},
{"dt":"迁西县"}
]}
]}
]
各位最好自己封装成插件，方便调用