Increasing the maximum ball passage of dredging pump can improve the continuity of the dredging project,reduce the risk of blocking the pump and improve the dredging construction efficiency.The maximum ball passage and efficiency of dredging pump are the contradiction in the design of dredging pump.Aiming at the above question,two kinds of schemes to increase the maximum ball passage of dredging pump are proposed,and the internal flow field of dredging pump of 3 schemes is calculated using numerical simulation method.By means of statistical analysis of the numerical simulation results,the performances of the three schemes are compared.The design scheme of the maximum spherical passage of dredging pump impeller is determined,which provides the basis for the subsequent improvement of dredging pump.