Abstract: The engine vibration is a major excitation source of submarine noise and requires substantial consideration during the structural design process. In this paper， an approach combining the finite element method with the boundary element method is proposed to calculate the underwater vibration of submarines with two different excitation sources - the propeller shaft and the engine. The acceleration effects on the submarine's engine pedestal， produced by the low frequency excitation force from the two sources mentioned above were also investigated. The obtained numerical results were compared and analyzed at different frequencies and power values. It was seen that the acceleration effects produced by the propeller shaft was quite small and could be safely neglected when the propeller shaft excitation was one order greater in magnitude than the engine vibration force. Overall， this observation could simplify and benefit the measurement of engine vibration characteristics in actual submarine applications.