Abstract: The plastic limit load of pipe elbows,not matter the failure model of the pipe elbows is plastic collapse or elastic-plastic fracture,is one necessary important parameter in the safety assessment.In the design of piping systems for nuclear power stations,the pressure and temperature is the work loads for pipe el-bows and also the main loads considered in the structural design of pipe elbows.Assuming the elbow material with ideal elastic-plastic behavior and considering the geometric nonlinearity,the distribution pattern of the plastic limit load in the pipe elbow under high temperature and pressure in the safety injection system is obtained using ANSYS.