Based on computer aided engineering technology, the injection molding of charging port cover is simulated, and the axial deviation of charging hole is calculated and analyzed. Through the analysis of gate matching and flow resistance, the best gate position and glue feeding scheme are determined. According to the initial process analysis, the shaft deviation of the large hole is 2.315 5 mm, which does not meet the design requirements. The orthogonal test was designed with process parameters as independent variables, and the axial deviation under different combination of process parameters was simulated and calculated, and the optimization scheme of process parameters was explored. The results show that the influence of mold temperature and injection time is extremely significant, the influence of velocity-pressure switching volume is significant, and the influence of barrel temperature is not significant. The optimized process parameter is A₁B₃C₁D₁. Through process optimization, the shaft deviation of the large hole is reduced to 0.854 9 mm, and the shaft deviation of the small hole is reduced to 0.692 9 mm, meeting the design requirements. Simulation and actual model test also verify the feasibility of the optimized process in practice.