Power electronic transformer is a new type of intelligent transformer which combines power electronic devices with high-frequency transformer. It will be the main power conversion and control link in the future distribution network,and it is also the key technology to realize the controllable ability of intelligent distribution network. This paper introduces the topological structure and working principle of power electronic transformer,according to the characteristics of power electronic transformer itself,a three-stage power electronic transformer simulation system based on Matlab/Simulink is established, and its operation is realized under two output control strategies.The waveform of each part of the system under different control strategies are compared. It has some reference value for the engineering application of power electronic transformer in medium voltage distribution network.