It was found that the noise of traction converter was prominent when a high-speed EMUs was running, resulting in a harsh whistle, which seriously affected the sound comfort. Aiming at this phenomenon, the acoustic tests of converter were carried out in the field and workshop. The acoustic characteristics were understood and the source of the whistle was determined. On this basis and concerning the converter structure and sound propagation characteristics, the optimization scheme of acoustic control was proposed and the acoustic simulation calculation and test verification were carried out for this scheme. The results showed that the optimization scheme could significantly improve the noise level of the converter and improve the comfort.