@model MvcWithAjax.Models.SoSoKe_Ad
@{
    ViewBag.Title = "Index";
}
<script type="text/javascript" src="../../Scripts/jquery-1.6.2.js"></script>
<h2>Index</h2>
<script type="text/javascript">
    $(function () {
        $("form").submit(function () {
            $.ajax({
                url: $(this).attr("action"),
                type: "post",
                data: $(this).serialize(),
                success: function (data) {
                    alert(data.msg);
                }
            });
        });
    })
</script>
@using (Html.BeginForm()) {
    <fieldset>
        <legend>广告</legend>
        <div>编号:@Html.TextBoxFor(model => model.Ad_ID)</div>
        <div>信息:@Html.TextBoxFor(model => model.Ad_Info)</div>
        <div>
            <input type="submit" value="提交" />
        </div>
    </fieldset>
}

    public class HomeController : Controller {
        //
        // GET: /Home/

        public ActionResult Index() {
            return View();
        }

        [HttpPost]
        public ActionResult Index(SoSoKe_Ad ad) {
            return Json(new { msg = "1" });
        }
    }

@using (Ajax.BeginForm()) {
    <fieldset>
        <legend>广告</legend>
        <div>编号:@Html.TextBoxFor(model => model.Ad_ID)</div>
        <div>信息:@Html.TextBoxFor(model => model.Ad_Info)</div>
        <div>
            <input type="submit" value="提交" />
        </div>
    </fieldset>
}

------解决方案--------------------

JScript code

 $("form").submit(function () {
      AJAX操作...
      return false;
 });