I am doing this project in mvc6 using asp.net framework 6.how I can add this reference in my project please help me.
You have to talk to BingAds and ask them for a compatible version. This is the same with every library provider, they all must support the new platform. You cannot add a library which targets .NET 4.x, they must rewrite and publish a new version/
来源：https://stackoverflow.com/questions/36194075/reference-is-not-added-in-asp-net-mvc-6-for-microsoft-bingads-sdk