To solve the problem of actually acquisition of seismic wave signal of the ship′s, the coupling principle between seismo-acoustic detection system and sediments is proposed. Based on the coupling theory, the vibration coupling relation between the detection system and the sediment is analysed, the mass-spring-damp model of vibration coupling is discussed. The transfer function of coupling model is studied by the analysis of vibration equation, the frequency response shows a character of the lowpass filter. Computation results are in agreement with experimental data. The result indicates that the amplitude and the phase of seismic wave are modulated by the vibration system. The influencing factors of coupling resonance are deduced. It can help to guide the design of seismo-acoustic detection system, improve the bandwidth and reduce the coupling influence.