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, a valve optimization design concept based on fault analysis is proposed. In-depth analysis of the root causes of the main pressure regulating valve faults, optimization and improvement design are carried out from the aspects of materials, structure and production technology according to the fault causes, and 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. The results show that the total pressure adjustment precision is increased to within 1.67% during the test process, and the newly developed pressure regulating valve structure is safer and more reliable, with good practical use effect and better pressure regulating characteristics.