In order to test the Correctness of output characteristics in different parts in the designing process of AC servo system and provide it with necessary design parameters, the speed of PMSM control system and a electric double closed loop simulation model of the vector control PMSM are established on basis of AC by using Simulink toolbox in Matlab. Moreover, MATLAB simulation is also conducted and on this basis come up with the design project using infineon XC878 chip to realize the PMSM vector control system. The system testing results show that it has the characteristics of quick start and response and high precision.A feasibility proposal is provided by the system to the research and development of PMSM vector control system based on MCU.