Abstract: The design of marine structures includes the structure design and the foundation design. While the calculation of wave force is quite crucial for the former, the evaluation of seabed stability is essential for the latter. The passage of a wave will impose wave pressures and shear forces on the seabed, and the wave-induced changes of pore water pressures and effective stresses within the seabed will make the seabed deform, soften and liquefy etc. Therefore, the evaluation of wave-induced seabed stability is important to the foundation design of marine structures, as well as to the superstructure design. Inspired from the mechanical properties of seabed, this article firstly suggests one simplified mechanical model, and then derives the soil displacement distribution of the two-dimensional seabed under wave action. In addition, two-dimensional finite element models are established, the results from which are compared well with those from the mechanical model. Such simplified model can be used in the evaluation of seabed stability and the response analysis of passive piles in the marine environment.