According to the balance design requirements of self-fan air-cooling metro permanent magnet traction motor for cooling effect and aerodynamic noise suppression, the cooling effect and aerodynamic noise of a metro permanent magnet traction motor with two cooling fans are numerically analyzed and experimentally studied. The main difference between the two fans is the outer diameter of the fan. The outer diameter of fan B is about 23% smaller than that of fan A. The research results show that compared with fan A, the ventilation quantity, static pressure and power consumption caused by fan B in the motor air duct are reduced by 29%, 47.4% and 53% respectively. Under the rated operating condition of the motor, the temperature rise of the motor caused by the flow reduction increases by about 9 K, which meets the design requirements of the motor temperature rise, and the corresponding aerodynamic noise is reduced by 3.3 dB(A), which has a good noise reduction effect.