@Ajax.ActionLink("Новый сайт", "newSite", "Publisher", new AjaxOptions { UpdateTargetId = "worksiteplace" })
<div class="col-md-12" id="worksiteplace">

        </div>

<div class="col-lg-8 col-md-8 col-sm-8 col-xs-8">
        @Html.DropDownList("CategoryList", ViewBag.CategoryListNewSite as SelectList, new { @class = "form-control" })
    </div>

public ActionResult newSite()
        {
            SiteAPI sa = new SiteAPI();
            List<siteCategory> lstCategory = sa.GetCategories("yardie", "75Hf654*");

            var datatCat = (from a in lstCategory select new SelectListItem { Text = a.name, Value = a.id.ToString(), Selected = false });
            ViewBag.CategoryListNewSite = datatCat;

            return View();
        }