Abstract: The 06Cr25Ni20 austenitic stainless steel seamless pipe experienced leakage during its service period. Through macroscopic observation and analysis，chemical composition analysis，metallographic examination，and scanning electron microscope examination，it is found that the wall thickness of the corrosion leakage area is obviously reduced， showing typical erosion corrosion characteristics. Based on the analysis of the pipe structure features，the thermodynamic property diagram of the material，and the characteristics of the corrosive medium，it is regarded that due to the pipe’s flow channel structure with a right-angle turn and a cavity can form vortices of the fluid，causing the accumulation and condensation of water vapor；and the operating medium in the pipe contains phosphorus trichloride that upon contact with water decomposes into highly reducing hydrochloric acid and hypophosphorous acid，leading to the destruction of the passive film formed on the material surface，and intensifying corrosion of the material at high temperature；owing to the continuous erosion by the operating medium，erosion corrosion occurs，and eventually leads to the leakage failure of said the seamless pipe.