To further improve the wave dissipation performance of permeable breakwater,this paper proposes a stepped breakwater structure based on the plate breakwater,and explores its wave dissipation performance in regular waves.A two-dimensional numerical model is constructed by Fluent software to analyze the effects of different lower baffle lengths,diving depths and wave heights on the transmission coefficient,reflection coefficient and energy consumption coefficient of the stepped breakwater,and the changes of the flow field around the structure are analyzed.The research results show that the transmission coefficient of the stepped breakwater decreases with the increase of the relative lower baffle length,relative wave height and relative diving depth.The reflection coefficient increases with the increase of the length of the relative lower baffle,and decreases with the increase of the relative wave height and relative depth.The energy consumption coefficient increases with the increase of relative lower baffle length,relative wave height and relative diving depth.