Abstract: The VELAN pneumatic valve experienced typical faults such as valve disc cracked and air leakage from the pneumatic head, during the installation and commissioning of the nuclear power plant project. In-depth analysis and research in this paper show that the root cause of valve disc cracked is the welding quality defect in the valve disc manufacturing process, resulting in increased brittleness, and the valve is subjected to overload stress during use, resulting in brittle cracking, and the treatment is to replace the valve disc assembly and packing, and to conduct a leak test. The root cause of leakage of the pneumatic head is that there is a deviation in the size of the O-ring, and insufficient compression causes leakage, the treatment is to increase the torque of the pneumatic rod center nut, tighten the torque, and then perform the sealing test again after the fastening is completed, or measure the thickness of the compensation ring and the size of the O-ring and process it, such as replacing the compensation ring or O-ring. Through the measures, the typical faults of VELAN pneumatic valves are effectively processed, which provides a reference for the analysis and treatment of similar problems in the future.