The noise of traction motor is composed of cooling fan noise, electromagnetic vibration noise and mechanical noise, in which the aerodynamic noise caused by cooling fan is an important part. The computational fluid dynamics(CFD) calculation model of the traction motor is established, and the DES-SST turbulence model is used to calculate the flow field in the traction motor. Through the streamline and vortex intensity distribution on the rotating surface and meridional surface, it is found that the flow separation phenomenon in the fan channel is very significant, and there is high-strength vortex motion at the fan air inlet and blade tip. The finite element calculation model for the aerodynamic noise of the traction motor is established，and the calculation result of the unsteady flow field is used as the sound source to predict the radiated noise of the traction motor. The calculation results show that the minimum difference of total sound pressure level at the noise monitoring points between the simulation calculated value and the test value is 0.1 dB(A), and the difference of average sound pressure level at multiple points between simulation and test is 1.8 dB(A). The calculation results are accurate. The aerodynamic noise of traction motor consists of discrete noise and broadband noise. The highest peak of discrete noise comes from the dipole noise of cooling fan, and the unequal spacing arrangement of fan blades causes the fundamental frequency of blade passing frequency to shift from 369 Hz to 221 Hz. At the same time, the radiation directivity of noise at this frequency presents a typical dipole characteristic and mainly propagates outward from the air inlet and outlet of traction motor. The research can provide reference for the noise reduction optimization of traction motor.