As the key component of the hydraulic control system of automatic transmission, the dynamic characteristics of multistage main pressure regulating valve directly affect the rapidity, stability and control accuracy of the system. When optimizing the structural parameters of the valve, the method of adjusting the parameters one by one with experience and then passing the test verification is inefficient and can not guarantee the optimal performance of the valve. A mathematical model of a multi-stage main pressure valve was established based on its working principle. The Simulink simulation model of the multi-stage main pressure regulating valve was built. By analyzing the influence of various structural parameters of multi-stage main pressure regulating valve on the dynamic response characteristics of valve inlet pressure, the spring stiffness, spring preloading shrinkage and damping hole diameter were selected as the variables to be optimized. The genetic algorithm provided in the MATLAB optimization toolbox was combined with Simulink to optimize the dynamic performance of the multi-stage main pressure regulating valve, and a test bench was built for experimental verification. The simulation and experimental results show that the optimized multi-stage main pressure regulating valve has good static characteristics, and the phenomenon of main pressure reducing when the load flow suddenly increases has been improved. The response time is short, and the dynamic performance is good.