Permanent magnet synchronous motor has been commonly adopted because of its compact structure, less noise, less power consumption, fast running speed and stable operation. Aiming at the weak magnetic control process of permanent magnet synchronous motor, the selection of speed ring parameters adopts the traditional PI (proportional-integral) control method, relying on the experience of parameter adjustment, the external anti-interference ability is poor, and it is difficult to ensure the excellent performance in each operation interval, etc. , a method of weak magnetic and MTPA (maximum torque per ampere) control of permanent magnet synchronous motor based on subtractive averaging optimization algorithm was proposed to provide a wide operation range method. Combining the intelligent optimization algorithm, MTPA control and weak magnetism control, the parameters of the PI (proportional-Integral) controller were optimized using the subtractive averaging optimization algorithm, which improves the system's response performance and anti-jamming ability. The operating voltage does not exceed the voltage limit circle using the MTPA control strategy. The operating voltage exceeds the voltage limit circle using the closed-loop feedback of the voltage, and the weak magnetism control was carried out. Using MATLAB/Simulink constructed permanent magnet synchronous motor weak magnetism control simulation simulation, through the PI controller and subtractive averaging optimization algorithm optimized PI controller performance comparison, from the simulation results to get the effectiveness of the controller method. The experiment effectively proves that the control method can solve the problem of optimized tuning of controller parameters under various operating conditions and improve the motor control accuracy.