Abstract: To study the dynamic pressure acting on the submerged floating tunnel (SFT) under the seismic SV wave in complex seawater environment, a theoretical analysis model is proposed considering the marine sediment effect. Based on the wave equations and displacement potential functions of different media materials, the theoretical equations of wave transmission and reflection coefficients at different interfaces are deduced and solved on MATLAB through the seismic SV wave propagation boundary. Numerical examples are employed to illustrate the effects of the saturation of the sediment, the incident SV-wave angle and the layout of tether on the dynamic pressure on the SFT. The results show that the unsaturated sediment has greater effect on the dynamic pressure on the SFT than that of the saturated sediment. Thicker sediment is more benefit to the SFT under the action of seismic SV wave. And increasing the tether stiffness or decreasing the tether spacing can reduce the dynamic pressure on the SFT.