Jquery返回大量Jason数据异常，怎么处理?

 $.ajax({
                    type: "POST",
                    url: "frmUnfinishActivity.asmx/GetData",
                    data: "{strRoot:'"+root+"',strNode:'"+node+"',strChild:'"+child+"'}",
                    dataType: "json",
                    contentType: "application/json",
                    success: success,
                    error: error
                });有直接配置参数的吗？设置Content-Length长度，或者配置web.config