In order to explore the optimum opening of highpressure pneumatic solenoid valve, and reduce noise and vibration during the working process, the internal flow field of the pneumatic solenoid valve was simulated by FLUENT software. The pressure and velocity distribution in the flow field of valve spool, and the force situation of seal ring were analyzed under different openings, according to which the optimum opening could be determined. Furthermore, the structure optimization of the nonuniform flow field was also carried out, and then the optimized and original flow structures were compared. The results show that the solenoid valve has more stable flow field and better work performance with the optimal opening, which is valuable for solenoid valve design.