The fit of the bearing with the end cover, shaft and wave spring washer has a great impact on motor NVH, so it is of great significance to calculate and analyze the fit tolerance of bearings and the selection of wave spring washers. This article discusses several factors that affect the bearing fit tolerance of automotive motors. Based on numerical calculation, theoretical analysis, simulation analysis and experimental verification, we propose the selection scheme of bearing and shaft, bearing and end cover tolerance, and puts forward the influence of wave spring washer on the rotor mode of the motor and the optimal scheme considering the NVH of the motor.