Abstract: The main noise sources and corresponding noise reduction measures of metro vehicle air-conditioning unit are analyzed. Through experiments, the noise reduction perfor-mance of sound-absorbing volute and sound-absorbing diversion circle commonly used in metro vehicle air-conditioning unit is tested, and the results are comparatively studied. It is found that the sound-absorbing volute has a good effect on reducing centrifugal fan noise with bare disturbance on fan performance, while the sound-absorbing diversion circle has neither noise reduction benefit nor disturbance on axial fan performance.