后台返回的数据：
"[
{
\"id\": \"1\",
\"pId\": \"0\",
\"name\": \"类别\",
\"open\": \"true\"
},
{
\"id\": \"A38C6434-A9F2-4C86-A4CC-F9C259C0E030\",
\"pId\": \"1\",
\"name\": \"青菜\"
},
{
\"id\": \"B0A6BF68-08CF-4AC9-BD09-F18B0CD9C3DF\",
\"pId\": \"1\",
\"name\": \"萝卜\"
},
{
\"id\": \"CB438203-BF32-4606-9AF6-621C553C5594\",
\"pId\": \"1\",
\"name\": \"黄瓜\"
},
{
\"id\": \"D45F148F-E077-4E88-8352-361E1B5028E6\",
\"pId\": \"1\",
\"name\": \"西红柿\"
}
]"
用Response.Write(str) 返回数据
前台：接受数据
$(document).ready(function () {
$.ajax({
type: "POST",
url: "Handle.aspx",
data: "ac=get&type=class",
success: function (msg) {
treeData = jQuery.parseJSON(msg);
var json = eval('(' + treeData + ')');
zTreeObj = $.fn.zTree.init($("#treeDemo"), setting, json);
},
error: function (xhr, msg, e) { alert(msg); }
}); });

跪求分析，初学实在是不懂啊！

补充，后台传到前台数据为
[
{
"id": "-1",
"name": "\u8003\u52e4\u7c7b\u522b",
"open": "true"
},
{
"id": "A38C6434-A9F2-4C86-A4CC-F9C259C0E030",
"pId": "-1",
"name": "\u7b7e\u5230"
},
{
"id": "B0A6BF68-08CF-4AC9-BD09-F18B0CD9C3DF",
"pId": "-1",
"name": "\u51fa\u53bf"
},
{
"id": "CB438203-BF32-4606-9AF6-621C553C5594",
"pId": "-1",
"name": "\u8fdb\u53bf"
},
{
"id": "D45F148F-E077-4E88-8352-361E1B5028E6",
"pId": "-1",
"name": "\u7b7e\u9000"
}
]

修改了一下前台，success 能正常执行了，但是数据还是不对

你这个数据怎么不对了？？ json 对象用alert 输出都是 object的。
请利用 chrome 的调试工具，利用console.log 进行输出调试