Taking self-ventilated traction motor as the research object, the characteristics of aerodynamic noise were analyzed in this paper, including the physical measurement of noise, identification and classification of aerodynamic noise. Through no-load noise test, the noise components of the prototype machine were analyzed and the main noise sources were identified. Based on CFD theory, the steady flow field of the whole motor was calculated to obtain parameters such as system wind resistance and velocity distribution. The motor aerodynamic noise was then predicted and evaluated according to flow characteristics. Noise reduction was achieved at the source by optimizing the design of the air inlet and outlet structures and the power fan. Meanwhile, an acoustic enclosure was used to control noise along the transmission path. The test results showed that the aerodynamic noise of the motor was significantly improved by adopting ventilation optimization design and acoustic measures at high rotational speeds 