这是我发现做到这一点，只需添加simpliest方式数据-VAL - * - * 在属性 HtmlAttributes DropDownListFor 时，视图中。下面的方法与RemoteValidation工作过，如果你不需要远程验证，只需删除包含数据-VAL-远程元素 - * ：

This is the simpliest way I found to do it, just adding data-val-*-* attributes in HtmlAttributes of DropDownListFor, inside the view. The following method works with RemoteValidation too, if you do not need remote validation, simply remove the elements containing data-val-remote-*:

        @Html.DropDownListFor(m => m.yourlistID, (IEnumerable<SelectListItem>)ViewBag.YourListID, String.Empty, 
        new Dictionary<string, object>() { { "data-val", "true" }, 
        { "data-val-remote-url", "/Validation/yourremoteval" }, 
        { "data-val-remote-type", "POST" }, { "data-val-remote-additionalfield", "youradditionalfieldtovalidate" } })

我希望这可以帮助。顺祝商祺！

I hope it may help. Best Regards!