This paper mainly studies the dynamic matching calculation and main parameter design of the whole vehicle. A practical design scheme for power system of pure electric vehicle is proposed and determined. According to the requirements of dynamic performance, the main parameters of the transmission system are designed and matched by using the knowledge of automobile theory. Through the simulation of the design scheme, the dynamic calculation of the scheme is carried out. The matching analysis of power system of extended-range electric vehicles is carried out in this paper. The power performance of pure electric vehicle is analyzed. In the process of power analysis, the data of maximum speed, gradient and acceleration are mainly analyzed, and the simulation results are analyzed. The simulation results show that the method proposed in this paper is effective and reliable.