To quickly get the all plastic injection parts, this article took advantage of the Mold flow Software to do a numerical simulation of all type plastic pump’s injection molding process ,determined the best gate location, designed the injection molding L9(33) orthogonal test table, chose mold temperature, melt temperature, injection pressure as the factors, conformed the shrink mark index, volume shrinkage ratio, maximum warping deformation and cavity residual stress for the parts's quality evaluation index, the orthogonal experiment was completed, and formulated the comprehensive quality evaluation indicators parts, utilized the modified simplex method to optimize transform function optimization into injection molding CAE optimization process, the injection molding process was optimized, which could obtain the injection molding optimum process parameters shown as follows: The mold temperature was 28.49℃, The melt temperature was 212.4℃,The injection pressure was 80.09MPa. The parts' comprehensive quality was that the shrink mark index was 0.0191%, volume shrinkage rate was 16.33%, maximum warping deformation was 1.516mm, and main direction's cavity residual stress value was 31.65MPa. It could obtain the wholly plastic pump by injection molding according to the optimum process parameters, and the parts met the requirement.