In order to reduce the axial force of the semi-open centrifugal pump with low specific speed, the influencing factors of the axial force of the semi-open centrifugal pump are analyzed and studied by means of orthogonal experiment by combining numerical analysis. The blade tip clearance and balance hole diameter are selected as experimental factors, and each factor takes 5 levels to carry out orthogonal design. SST k-ω Turbulence equation is used to calculate the axial force of the semi-open centrifugal pump. According to the comparison between the calculated results and the experimental results of the original model, it is found that the head and efficiency change within 5%, so the numerical simulation method is feasible. Based on L25 (5²) orthogonal table, 25 groups of experimental schemes are designed, and the optimal scheme is obtained by analyzing the numerical simulation results of 25 groups of experimental schemes. The results show that by reducing the tip clearance and establishing the balance hole, the back cavity pressure increases significantly, and the axial force of the centrifugal pump decreases greatly, the maximum reduction is 440.59 N, accounting for 45.6% of the total axial force of the original model. At the same time, it has little effect on pump performance, efficiency only reduces by 3.76%, and the head reduces by only 0.3%. [ABSTRACT FROM AUTHOR]