Abstract: During the operation of the motor, the thermal deformation of parts caused by internal heating can affect the uniformity of the motor air gap, resulting in the air gap accuracy not meeting the requirements. Therefore, in the design of the motor, the impact of thermal deformation on the assembly accuracy of the motor needs to be considered. To address this issue, firstly, the temperature of each component under the specified working state is obtained through motor thermal testing, and its thermal deformation is calculated using finite element simulation. Secondly, a polyhedral model of motor tolerance under thermal deformation is constructed, and the radial variation of motor air gap is obtained through Minkowski summation and intersection calculation. Finally, the geometric tolerance values of the parts is adjusted and optimized to ensure that the air gap accuracy meets the design requirements.