Aiming at the problem that the reliability of the main pressure regulating valve DN2000 in a supersonic wind tunnel is reduced due to the wear of moving parts and serious structural vibration, the optimal design concept of the valve based on fault analysis is put forward. Firstly, the root causes of the main pressure regulating valve faults are analyzed in depth, and then the design is optimized and improved from the aspects of material, structure and production process according to the fault causes. The reliability of the valve is improved by improving the support mode of the valve core, optimizing the internal structure of the valve body, improving the sealing performance and improving the stiffness of the displacement sensor. During the test, the total pressure adjustment accuracy is improved to less than 1.67%. The results of strength analysis and modal analysis show that the newly developed pressure regulating valve structure is safer and more reliable, and the actual use effect is good, and the pressure regulating characteristics are better.