Aiming at the temperature rise problem of drive motor for electric vehicle under extreme conditions, the numerical method of fluidsolid conjugate heat transfer was used to simulate the heat dissipation performance of a permanent magnet synchronous motor. The temperature distribution of the stator and rotor under different working conditions was obtained. The slip ring module was used to solve the problem of rotor temperature rise test. The data of temperature rise test and computational fluid dynamics (CFD) simulation results of different vehicle conditions were compared to verify the accuracy of the numerical model and method. This research provided theoretical support for accurately obtaining the operating temperature of permanent magnets in the motor under driving conditions.