In this paper, starting from the water inlet mode, taking the self-balancing multistage centrifugal pump as the research object, the influence of the water inlet balancing device on the performance of the suction chamber of the self-balancing multistage centrifugal pump is explored. The distance between the center of the balance water pipe and the outlet of the water entry balancing device and the diameter of the balance water pipe were taken as design variables. 5 groups of different comparison schemes were constructed based on the equally spaced control variable method. The external characteristics, pressure distribution, velocity streamline distribution and cavitation performance of the 5 groups of schemes were simulated and analyzed by CFD method. The results show that the head and efficiency of the self-balancing multistage centrifugal pump can be affected by the presence, location and size of the balance water pipe. In the test scheme, the range of centrifugal pump head is 2 m and the range of efficiency is 0.27 percentage points. As the distance between the center of the balanced water pipe and the outlet of the water inlet balancing device or the diameter of the balanced water pipe becomes smaller, the high pressure area in the suction chamber increases obviously, while the eddy current density decreases obviously, and the flow line becomes smoother. The cavitation area in the suction chamber decreased significantly, and the maximum volume fraction of the suction chamber of the optimized scheme was 90.91%, which was 5.4% lower than the maximum volume fraction before optimization. This study can effectively improve the performance self-balancing multistage centrifugal pump suction chamber, and provide a basis and reference for optimization and design of multistage centrifugal pump.