/// <summary>

     /// MESService 的摘要说明

     /// </summary>

     [WebService(Namespace = "http://tempuri.org/")]

     [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

     //[System.ComponentModel.ToolboxItem(false)]

     // 若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消注释以下行。

     [System.Web.Script.Services.ScriptService]

     public class MESService : System.Web.Services.WebService

     {

         [WebMethod(Description = "")]

         public string GetDataReturnStr(string strXML)

         {

             //你的结果处理

             #region 处理数据

             #endregion

             return Common.JsonHelper.SerializeToJson(new Student() { id = "", name = "测试" });

         }

     }

     [Serializable]

     public class Student

     {

         public string id { get; set; }

         public string name { get; set; }

     }

<system.webServer>

    <!--解决跨域请求 -->

    <httpProtocol>

      <customHeaders>

        <add name="Access-Control-Allow-Methods" value="OPTIONS,POST,GET" />

        <add name="Access-Control-Allow-Headers" value="x-requested-with,content-type" />

        <add name="Access-Control-Allow-Origin" value="*" />

      </customHeaders>

    </httpProtocol>

</system.webServer>

<system.web>

    <webServices>

      <protocols>

        <add name="HttpSoap"/>

        <add name="HttpPost"/>

        <add name="HttpGet"/>

        <add name="Documentation"/>

      </protocols>

    </webServices>

</system.web>

 $.ajax({

                 async: true,

                 type: "post",

                 url: "http://localhost:41453/IDataServer/MESService.asmx/GetDataReturnStr",

                 data: "{strXML:'123123123'}",

                 dataType: "json",

                 contentType: "application/json; charset=utf-8",

                 success: function (json) {

                     var dataObj = eval("(" + json.d + ")");

                     alert(dataObj.id + '\r\n' + dataObj.name);

                 },

                 error: function () {

                 },

                 complete: function () {

                 }

             });