1. 真的没有必要，除非你坚持的值为0做到这一点。该在HtmlHelper DropDownList的扩展允许您设置一个选项标签，显示了在选择一个空值的初始值.a个DropDownList的签名，有该选项的标签。<%= Html.DropDownList( "DropDownValue",      (IEnumerable<SelectListItem>)ViewData["Menu"],      "-- Select One --" ) %>2. 我得到这个通过填充一个SelectItemList，转换为一个列表，并在索引0添加一个值来工作。List<SelectListItem> items = new SelectList(CurrentViewSetups, "SetupId", "SetupName", setupid).ToList(); items.Insert(0, (new SelectListItem { Text = "[None]", Value = http://www.mamicode.com/"0" }));ViewData["SetupsSelectList"] = items;3. public static SelectList IndividualNamesOrAll(this SelectList Object)   {    MedicalVarianceViewsDataContext LinqCtx = new MedicalVarianceViewsDataContext();    var IndividualsListBoxRaw =        (        from x in LinqCtx.ViewIndividualsNames //not correct need individual view!        orderby x.FullName        select x        );    List<SelectListItem> items = new SelectList           (            IndividualsListBoxRaw, "First_Hospital_Case_Nbr", "FullName"           ).ToList();    items.Insert(0, (new SelectListItem { Text = "All Individuals", Value = http://www.mamicode.com/"0.0", Selected = true }));    Object = new SelectList       (       items,"Value","Text"       );    return Object;   }4.private SelectList AddFirstItem(SelectList list)  {   List<SelectListItem> _list = list.ToList();   _list.Insert(0, new SelectListItem() { Value = http://www.mamicode.com/"-1", Text = "This Is First Item" });   return new SelectList((IEnumerable<SelectListItem>)_list, "Value", "Text");  }这应该做你需要的，只是发送您的选择列表 CodeGo.net，它会返回一个选择列表中的一个项目索引0 您可以将文字，值或项目，甚至索引你需要插入5. 使用C#扩展方法static public class SelectListHelper{ static public SelectList Add(this SelectList list, string text, string value = http://www.mamicode.com/"", ListPosition listPosition = ListPosition.First) {  if (string.IsNullOrEmpty(value))  {   value = text;  }  var listItems = list.ToList();  var lp = (int)listPosition;  switch (lp)  {   case -1:    lp = list.Count();    break;   case -2:    lp = list.Count() / 2;    break;   case -3:    var random = new Random();    lp = random.Next(0, list.Count());    break;  }  listItems.Insert(lp, new SelectListItem { Value = http://www.mamicode.com/value, Text = text });  list = new SelectList(listItems, "Value", "Text");  return list; } public enum ListPosition {  First = 0,  Last = -1,  Middle = -2,  Random = -3 }}用法（由为例）：var model = new VmRoutePicker {  Routes =  new SelectList(_dataSource.Routes.Select(r => r.RouteID).Distinct())  };           model.Routes = model.Routes.Add("All", "All", SelectListHelper.ListPosition.Random);//or model.Routes = model.Routes.Add("All");6. 听起来可能不是很优雅，但这样做： var items = repository.func.ToList(); items.Insert(0, new funcItem { ID = 0, TextValue = http://www.mamicode.com/"[None]" }); ViewBag.MyData = new SelectList(items);7. 这是可能的。//Create the select list item you want to addSelectListItem selListItem = new SelectListItem() { Value = http://www.mamicode.com/"null", Text = "Select One" };//Create a list of select list items - this will be returned as your select listList<SelectListItem> newList = new List<SelectListItem>();//Add select list item to list of selectlistitemsnewList.Add(selListItem);//Return the list of selectlistitems as a selectlistreturn new SelectList(newList, "Value", "Text", null);8. 我不知道如果任何人有一个更好的选择...<% if (Model.VariableName == "" || Model.VariableName== null) { %> <%= html.DropDpwnList("ListName", ((SelectList) ViewData["viewName"], "",   new{stlye=" "})%><% } else{ %><%= html.DropDpwnList("ListName", ((SelectList) ViewData["viewName"],   Model.VariableName, new{stlye=" "})%><% }>