I want to add data in dropdown list from database using MVC.please help me out?

You have to pass a SelectList instance to the view. You can either add it to the viewbag (or to the viewmodel) like this:

ViewBag.DropDown = new SelectList(IEnumerable of elements to be listed in the dropdown, "element field to be used as index", "element field to be used as display text")};

Than you can use it in your view:

@Html.DropDownList("DropDown")

Of course consult MSDN for other features:
http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist.aspx[^]
http://msdn.microsoft.com/en-us/library/system.web.webpages.html.htmlhelper.dropdownlist(v=vs.99).aspx[^]