Aiming at the problem that the reliability of the DN2000 main pressure regulating valve in a supersonic wind tunnel decreases due to the wear of moving parts and serious structural vibration, the valve optimization design concept based on fault analysis is proposed. In-depth analysis of the root causes of the main pressure regulating valve failure, according to the causes of the failure from the material, structure and production process to carry out optimization and improvement design, through the improvement of the valve core support mode, optimize the internal structure of the valve body, enhance the sealing performance and improve the stiffness of the displacement sensor to improve the reliability of the valve. The results show that the total pressure regulation accuracy is improved to ± 1.67% during the test, the structure of the newly developed pressure regulating valve is safer and more reliable, the actual use effect is better, and the pressure regulation characteristics are more excellent.