ASP.NET MVC framework is a mainstream technology for developing Web applications in the future. This paper describes how to transfer a Web Forms application based on multi-tiers architecture and ASP.NET 4 technology to a ASP.NET 4 MVC framework for multi-tiers architecture. From the perspective of multi-tiers architecture, the working principle of MVC mode is analyzed, and a MVC 4 ASP.NET customer relationship management system is given.