Based on Ansys multiphysics simulation platform, a multiphysics coupling analysis of a vehicle asynchronous motor was carried out. The temperature rise and thermal stress of the motor under the rated working conditions and the peak operating conditions were simulated, and the temperature field distribution of each part of the motor was analyzed deeply, and the maximum allowable time of the motor peak condition was predicted. The thermal stress distribution of the internal structure of the rotor was analyzed by finite element simulation of the thermal structure. The thermal stress of the rotor bar and the end ring welding position and the interference surface of the rotor and the core were analyzed. Whether the rotor bar and end ring welding position of the risk of welding, and through the thermal simulation and stress analysis, the value of interference fit that the shell and the core does not occur sliding or rising in the maximum temperature rise conditions.