Combined with the hydraulic design, regression orthogonal test and Computational Fluid Dynamics, this research concentrated on improving the efficiency of stamping well pumps. An L18（37）orthogonal test was designed with seven geometrical parameters and three levels including impeller outlet slope, blade outlet placed angle, blade inlet placed angle, blade outlet width, impeller blade number, guide vane blade number and guide vane inlet width. 18 programs were designed. Well pumps at rated point in the whole flow field were simulated through the standard model, SIMPLEC algorithm and second-order upwind scheme by Fluent. The influence law of geometrical parameters on efficiency and head were discovered by orthogonal analysis. Specifically, impeller outlet slope, blade outlet placed angle and blade outlet width exert the most significant influence on pump efficiency. 16 impellers were designed under the quadratic regression orthogonal test with these three factors. Through quadratic regression equation the function relationship between efficiency values and three factors was fit. As well as the analysis of the regression equation, the optimal combination of geometric parameters could be found and stainless steel stamping well pump with high efficiency could be designed. The result would be instructive to the optimization of stamping well pump that are designed by the impeller maximum diameter method.