In order to reduce the temperature rise of the traction motor windings and improve the flow efficiency of the external flow field of the motor，a permanent magnet synchronous traction motor for locomotives is taken as the research example. According to the actual size of the motor, models of the motor’s external air flow field, stator core and windings are established. Based on the principle of computational fluid dynamics (CFD), the flow field of the external air path of the motor is numerically simulated, the flow of the external air path of the motor is calculated for different stator vents, and the coupled turbulent flow and temperature fields of the stator core and windings are calculated and analyzed. Through calculation and analysis, the best design scheme of stator vents is obtained, which provides reference for the design of stator vents of this type of motor.