Abstract: The imported equipment LW25-252 circuit breaker in a 220 kV station is a single air supply pneumatic mechanism. Due to the long running time of the internal pneumatic valve, the aging of the sealing ring causes frequent air leakage of the pneumatic valve. This article studies the VA133 and VA134 pneumatic valves in the station's LW25-252 circuit breaker. After disassembling the pneumatic valves, analyzing the working principle and the role of the seals in each part, it is determined that the piston rod sealing ring in the valve body is the source of air leakage in the pneumatic valve, developed special tools based on the valve body piston rod structure for disassembling and assembling the valve body, and further simulated the centralized air supply mode to design a pneumatic valve body inspection platform to conduct self-test and self-inspection of the repaired pneumatic valves to realize the VA133 and VA134 of the manufacturer. The pneumatic valve is self-disassembling, self-repairing and self-inspecting, reducing dependence on external manufacturers for assistance.