Vibration performance is an important indicator to evaluate the torpedo power system. The torpedo power cabin is abstracted as a lumped parameter dynamic model composed of vibration source，transfer path and response point. The dynamic equation is derived in the frequency domain and the amplitude expression of the steady-state response is obtained. Combined with the concept of insertion loss in electrical system，the velocity insertion loss indicator for evaluating the effect of isolation component in torpedo power cabin is proposed. The velocity insertion loss evaluation formula of different vibration transfer paths is given by means of vibration path isolating. Combined with the engineering problem，a numerical example is given，which shows that the performance parameters of the power cabin isolation structure can be clearly planned at the beginning of the design.
