A modeling method of a stator winding air gap for temperature field analysis of an AC traction motor includes: changing the width of an air gap of a stator winding equivalent model according to a set value of spacing; establishing a three-dimensional finite element model of the AC traction motor with the stator winding air gap; based on the three-dimensional finite element model of different widths of the air gap, analyzing a temperature field to obtain a temperature field distribution diagram of the AC traction motor; carrying out the numerical fitting according to data in the temperature distribution diagram to obtain a function relation between the air-gap width and the temperature of the stator winding equivalent model; and by measuring the actual temperature of a motor stator winding, calculating an optimal air-gap width corresponding to the modeling of the stator winding of the current AC traction motor.