The problem of regression is widely used in scientific, technical, socio-economic... handle tasks such as trend analysis of the evolution of the phenomenons, computational optimization, forecasting... In software engineering, design patterns as a general solution to the common problems in software design. In this article, the authors will build and design the model solve regression problems based on the designs that Gamma has proposed. From there take a deeper look at some of the designs, as well as learn the new features of C# language makes it easier to design objectoriented software.