There has been an increasing need to migrate legacy systems to new hardware technologies and software development paradigms because the legacy systems present problems such as low effectiveness and high maintenance. If organizations want to remain competitive in today’s fast changing business and technological environment, they must overcome these problems. Middleware is a valuable technology in that it provides convenient methods to construct system infrastructure, so it can be used to migrate the legacy systems. This paper gives a case study on using middleware technologies for the implementation of reengineering distributed and heterogeneous bank legacy system in Anhui branch of China Construction Bank. Using middleware to migrate legacy system has proved to be good choice in practice. There has been been an increased need to migrate legacy systems to new hardware technologies and software development paradigms because the legacy systems present problems such as low effectiveness and high maintenance. If organizations want to remain competitive in today’s fast changing business and technological environment, they must overcome these problems. Middleware is a valuable technology in that it provide you to facilitate methods to construct a system infrastructure, so it can be used to migrate the legacy systems. This paper gives a case study on using middleware technologies for the implementation of reengineered distributed and heterogeneous bank legacy system in Anhui branch of China Construction Bank. Using middleware to migrate legacy system has proved to be good choice in practice.