Abstract: The turbocharging boost ratio of internal combustion engines is increasing with the requirements of power intensification and power recovery at high altitudes. High turbocharging technology has become one of the key technologies in advanced internal combustion engines area. The increase of the pressure ratio will lead to a sharp decrease in the stable working range and the efficiency of centrifugal compressor. The aerodynamic stability and working range expansion of the high-pressure-ratio centrifugal compressor become a core research area. In order to broaden the stable working range,a centrifugal compressor with blade casing was studied using numerical simulation to investigate the internal flow characteristics and stability mechanism. The blade form was optimized,and finally verified by experiments. The test results show that the optimized guide vane casing structure can effectively broaden the flow range of the high-pressure-ratio centrifugal compressor,and the surge flow range is expanded by 6%-8%.