Abstract: The charge valve in missile launcher was found to have fractured after service for a while in a naval base, and separated from the body of cylinder. The fracture cause was analyzed by fracture observation, micro-structure examination, energy spectrum analysis. The reason lies in that the charging valves, with their shell material in poor condition and the specification being impropriate, are sensitive to stress corrosion. Stored in wet salt fog atmosphere in coastal areas, and under the effect of internal pressure and assembly pre-tightening force, the charging valves produce thread tensile stress at the end of thread relief groove, which leads to the stress corrosion fracture after stored for a period of time. This paper puts forward some effective suggestions for subsequent product testing and production, and takes effective measures to use 15-5PH as charging valve replacement material. This improvement measures provide the basis and experience for the design, material selection and the engineering application of charge valve in missile launcher in future.