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The low specific-speed centrifugal pump with the specific speed of 26 was selected to be the numerical model. Under the condition of other geometric parameters of the volute and impeller maintained constant, the radial reflux balance hole, the traditional axial balance hole and none balance hole were designed to couple with the low-specific centrifugal impeller respectively. Based on the continuity equation, momentum equation, standard k—ε turbulence model, homogeneous multiphase model and Rayleigh—Plesset equation, the cavitation performances of the pump with different reflux balance holes were simulated. The trend of simulated H—LNPSHa curves were consistent with the experimental data, in addition, the accuracy of numerical simulation was also verified. The results showed that with equipped radial reflux balance hole, the anti-cavitation performance of the pump can be improved obviously due to the coincidence between the balance-hole backflow with impeller inflow. 