In view of the low speed performance shortage of China 6 engine with EGR, the aerodynamic performance optimization of compressor impeller was conducted from the average meridian profile of impeller and the load distribution of blade aspects. The simulation analysis and comparison were further carried out by using NUMECA 3D fluid simulation software. The results show that the compressor pressure ratio and efficiency  improve and the peak efficiency increases by 3% after optimization. According to the analysis of flow field, it is found that the static pressure of new impeller increases evenly along the flow direction, which reduces the flow loss. The loss in the tip clearance area also reduces. The mixing loss of fluid through the outlet of impeller is low, which makes the diffusion loss of fluid in the diffuser reduce. The feasibility of design scheme is finally verified by the performance test on the compressor bench. Considering the more attention to low speed performance and EGR demand, the turbine volute A/R reduces by 8% and matches with the new compressor, and then the test was conducted on the engine bench. It indicates that the low speed torque of engine increases by 1.3%, the low speed fuel consumption reduces by 1.7%，and the pressure difference is slightly better than the target pressure difference at medium and low speed. Accordinly, the engine performance and EGR level can meet the requirements of engine manufacturer.