升级到MVC 5.1，你可以在EditorFor中使用HTML属性：

Upgrade to MVC 5.1 and you can use HTML attributes in EditorFor:

@Html.EditorFor(m => m.variable, new { htmlAttributes = new { placeholder = "Your Placeholder Text" } })

http://www.asp.net/mvc/overview/releases/mvc51-release-备注