In order to increase the flow rate of the supercharger used in a plateau heavy-duty vehicle, a method of impeller design is presented. In this method, the impeller blade profile is divided into two sections along the flow direction. The section at the inlet remains unchanged, while the section at the outlet takes the blade torsion angle as the uniform load according to the blade outlet Angle, so as to ensure that the geometric Angle of the impeller profile increases at the same speed in the radial direction of the impeller. Using this method, the impeller design of different blade outlet angles is completed, and the finite element model is established. The calculation results show that when the blade outlet Angle is increased, the flow rate of the supercharger will increase significantly, but when the outlet angle is greater than 90°, the flow rate increase is not obvious, and the pressure ratio is very sensitive to the flow rate change, also the blade load increases.