In the rocket turbopump, the balancing system with the balance piston is often applied to reduce the axial thrust. The leakage flow through the balance piston is affected by the configuration of the balance piston and the balancing point in the axial direction. In designing the internal flow system, the balancing point and flow rate have been estimated by the static analysis code of the internal flow. On the other hand, the analysis code for dynamic response of the internal flow through the balance piston was developed. In this study, optimal calculation considering the dynamic characteristics of the internal flow system was carried out by using the dynamic analysis code. As the results, the balancing point in the steady state significantly affects the leakage flow rate and the axial vibration.