Centrifugal compressor is the core component of turbocharger, which usually uses vane diffuser for the high pressure ratio. Compared with vaneless diffuser compressor, the vane diffuser with the same diameter ratio has larger diffused pressure stability and higher efficiency. However, the efficiency of vane diffuser is lower than vaneless diffuser at offdesign points because of the influence of vane attack angle and the stable work flow range becomes narrow. For the stability improvement of centrifugal compressor, an asymmetric distribution vane diffuser was put forward by studying the effects of volute asymmetric structure on diffuser internal flow and changing the vane distribution form and setting angle of diffuser at the throat of volute. The variation of internal flow for vane diffuser was further analyzed and verified by bench test. The results show that the asymmetric vane diffuser can expand the flow range by around 10% at the high pressure zone of compressor.