This paper analyzed the present research situation of the permanent magnet synchronous motor system, and designed the variable frequency regulation speed system using TMS320F2407 as the control core. Firstly, the structure of hardware and software of the system were introduced. Then the working principle and control method of the PMSM vector control were analyzed and the mathematical modeling of permanent magnet synchronous motor servo system was built. On this basis the PI controller was designed and used in permanent magnet synchronous motor variable frequency speed control system. Finally the system was simulated using the MATLAB simulation tool, and the simulation results show that the system not only can adapt to the changes of object parameters, but also eliminate the steady state error and obtain a higher control precision for the permanent magnet synchronous motor with the characteristics of nonlinear, strong coupling and the parameters excursion.