Aiming at the difficulty of heat dissipation during long-term operation of in-wheel motor electric vehicles，a matching cooling mechanism and cooling method are designed. On this basis，a thermal and magnetic coupling temperature field simulation model of the in-wheel motor is established. Under the two operating conditions，the thermal and magnetic coupling temperature rise of in-wheel motors based on different cooling sources and multi-mode modes are carried out，and the simulation results are verified by experiments. The results show that the motor high-temperature problem is significantly improved during the long-term operation of electric vehicles; the two operating conditions have different effects on the motor temperature rise. The simulation results are in good agreement with the test results. The maximum winding error in working condition 1 is 5.1%，the maximum rotor error is 4.9%，the maximum winding error in working condition 2 is 4.8%，and the maximum error of the rotor is 4.5%. The study of high-temperature problems during long-term automobile operation provides a certain reference.