Aiming at the problem that the carrier vibration of underwater detection system interferes with the micro-Doppler spectrum of target echo signal, the approximate multiplicative expression of interference was derived from the basic principle of interference generation. With obtaining vibration interference data, an interference suppression algorithm for multiplicative interference was proposed. Meanwhile, the error caused by the approximate algorithm was analyzed according to the approximate conditions when the multiplicative expression of interference was derived. Simulation results show that the proposed method can effectively suppress the interference which is derived from vibration of underwater acoustic detection system and imposed on the micro-Doppler spectrum, and the algorithm error can be ignored generally.