Taking a self-fan-cooling traction motor as an example, the wind resistance, air volume, flow rate, mechanical loss and aerodynamic noise of the motor ventilation system are analyzed by using computational fluid dynamics (CFD) method, and the experimental verification is carried out. The results show that improving the uniformity and stability of the air flow in the fan and reducing the fan vortex can significantly improve the fan performance and reduce the fan loss. After optimization, the aerodynamic noise of the motor is obviously reduced and the efficiency of the motor is significantly improved, improving the performance of the motor. The calculation and analysis method and the conclusion have certain reference significance for the improvement of motor fan performance.