Combined with the technological features of stamping pump, numerical simulation based on Fluent was made for 100XQJ8—43/9 stamping well pump. In order to improve the accuracy of numerical calculation, numerical calculation of stamping well pump model of different blade thicknesses was carried out by using different grid numbers and different stage models. The relationship between the blade thickness and the overall performance of pump was analyzed from the external characteristics and internal flow field. In conclusion, with the increase of blade thickness, the best efficiency point of pump shifts to the small flow direction and the internal turbulence losses of pump were increasing gradually. Through the experiment of the mode pump, the numerical simulation values under the whole flow field are much closed to the experimental values and the error is less than 1%, which verified the feasibility of numerical simulation. The text would be instructive to the optimization of new-type well pump which is designed by the impeller diameter maximum approach.