A winding air gap optimization modeling method is proposed to address the problem of irregular air gaps between the stator windings of an AC traction motor and the inaccuracy of the model built by conventional equivalent modeling methods. In this paper, the basic structure of the stator winding equivalent model is determined, and the optimal width of the winding air gap in the equivalent model is proposed, i.e., according to the equivalent air gap model and using the finite element method to analyze the temperature field of the motor to obtain the temperature value corresponding to a certain point on the winding model surface. The best air gap width corresponding to the equivalent air gap model can be obtained according to the functional relationship obtained and the actual temperature corresponding to a point on the surface of the model. This method effectively improves the accuracy of the stator winding modeling of an AC traction motor, thus significantly improving the accuracy of its temperature field analysis, and has good application value. This work is supported by the Scientific Research Project of Hunan Education Department (No. 19C0791).