In order to solve the problems of the lack of design basis, low efficiency of artificial experience design and difficulty to maximize the wave dissipation of new multi-stage platform of ecological seawall, a three-dimensional mathematical model coupled with the high-precision capture algorithm of water-gas interface was built. Then, this model was used to study the wave dissipation characteristics and wave overtopping calculation of multi-stage platform of ecological seawall. Considering the overtopping laws of wave under different combinations of dike structure (step width, step height and dike height), a formula for calculating the wave overtopping of multi-stage platform of ecological seawall is put forward. The results show that with the gradual elevation of multi-stage platforms, the thickness of overlying water on the breakwater becomes smaller, resulting in the energy dissipation of continuous breaking of waves. At the same time, the multi-stage platforms block the propagation of shallow waves by stages, forcing the waves to reflect step by step and attenuate. The width and height of the multi-stage platform jointly control the overtopping of the breakwater. It is found that the longitudinal height and transverse width of the multi-stage platform have a quantitative exchange relationship under the same overtopping situation.