[AjaxPro.AjaxMethod] public string Ajax_Getstr() { return "39.01235,118.0456782"; } There are functions in Javascript as follow: function Getstr() { var str0 ="21332,678"; var arr0 = new Array(); arr0 = str0.split(","); alert(arr0[0]);//here display is "21332",very good var str1 = _Default.Ajax_Getstr(); alert(str1.value);//so far, all is well var arr1 = new Array(); arr1 = str1.split(",");//display error alert(arr1[0])//here diaplay undefined }