In order to investigate unsteady hydrodynamic performance of integrative propulsion system, integral solution based on panel method is used to calculate the system. Interaction between propeller and rudder is considered by recalculating influence coefficents. Influence of propeller wake to rudder is studied, and then propulsion performance of integrative propulsion system is calculated in steady flow. Calculation results is compared with steady value and indicates that it’s feasible to use this method for predicting the unsteady performance of integrative propulsion system.