不好意思，已经自己搞定了
//初始化树
function initTree()
{
multiSelect = $("#multiSelect").val();
if(multiSelect=="1"){setting.check.chkStyle="checkbox";}
$.fn.zTree.init($("#ztree"), setting,null);
zTree = $.fn.zTree.getZTreeObj("ztree");
}

setting师哥json对象，你在var treeObj = $.fn.zTree.init($("#earaTree"), allAreaSetting,result);之前修改里面的值就可以了；例子如下：
var setting = {
data: {
simpleData: {enable: true,idKey: "id",pIdKey: "pId",rootPId: 0}
},
check: {
enable: true,
chkStyle: "radio",
//chkStyle:function(){if($("#multiSelect").val() == "0"){return "radio";}else{return "checkbox";}},
radioType: "all"
}
};
//从后台获取json对象后：
//从后台获取数据 显示树
function init() {
$.ajax({
cache : false,
asunc:false,
type : "post",
dataType : "json",
url : projectName + "/area/getCurrUserAllArea",
success : function(result) {
console.info("get area tree success");
if (result == null || result == '') {
$("#earaTree").html("暂无数据");
} else {
// treeNode = result;
var multiSelect = 0; //从页面获取
if (multiSelect==1) {
setting .check.chkStyle = "checkbox";
} else{
setting .check.chkStyle = "radio";
};
var treeObj = $.fn.zTree.init($("#earaTree"), setting ,result);
}
}
});
}

async: {
enable: true,
type: "post",
url: "/homepage.nsf/ajaxGetTreeNodesInfoForSelect?openAgent",
dataType: "json",
autoParam:["id=pId"]
//,otherParam:{"curUserName":function(){return curUserName;}}
}
--------------------
上面注释那行是可以的