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Cavitation is a physical phenomenon of centrifugal pump internal flow, during the operation of centrifugal pump, cavitation will directly lead to deterioration of hydraulic performance, and it seriously affects the safety and stability of the pump system. Therefore, it is of great significance to seek ways to improve the cavitation performance of centrifugal pump for safe and stable operation of centrifugal pump system. In order to further improve the cavitation characteristics of centrifugal pump，a method to suppress cavitation by moving the balance hole to the back of blade was proposed. According to the characteristics of centrifugal pump cavitation flow field，based on RNG k-ε turbulence model and Zwart-Gerber-Belamri cavitation model，the cavitation flow field with different cavitation numbers in the model before and after balance hole offset was calculated and analyzed. The results showed that compared with the experimental values of the original model, the head was decreased within 4% and the efficiency was decreased within 5% after balance hole offset. The critical cavitation number was decreased after the balance hole offset at flow rates of 1.2Qe, Qe and 0.8Qe. After the offset of balance hole, the distribution of static pressure zone on the back of the blade was changed. And the velocity in the low-pressure area on the back of the blade was reduced, at the same time, the turbulent kinetic energy in the flow passage can be effectively improved and it can inhibit the cavitation at all stages. Balanced hole offset can effectively reduce the volume fraction of the flow passage, improve the flow condition in impeller runner and reduce the blockage of flow passage by cavitation. The bubble volume in impeller was decreasesd obviously after balance hole offset and the fluctuation amplitude was decreased in a rotation period. The axial force was reduced and the mechanical condition of centrifugal pump was improved.