Abstract: In order to study the influence of changing step shape on the energy dissipation characteristics of stepped spillway, a keyboard-stepped energy dissipator was proposed, the water surface profile and flow pattern characteristics, pressure characteristics, velocity vector characteristics and energy dissipation rate of the keyboard-stepped energy dissipator and traditional stepped energy dissipator under different flows were analyzed by the combination of numerical simulation and model verification. It can be concluded that at Q=40 m~3/h, the flow pattern of the keyboard-stepped energy dissipator is still drop flow while the traditional stepped energy dissipator is transition flow, and the flow pattern of the keyboard-stepped energy dissipator is relatively stable. The pressure distribution on the surface of the keyboard-stepped energy dissipator at different flows shows that maximum pressure areas and negative pressure areas are not distributed on both sides of the step convex angle and the distribution is relatively scattered, which has less influence on the step convex angle and is more conducive to maintenance. At the same time, there are many three-dimensional vortex near the key steps, which can consume the kinetic energy of water better. Furthermore, the energy dissipation rate of the keyboard-stepped energy dissipator is more stable than that of the traditional stepped energy dissipator at different flows. The maximum decrease of the energy dissipation rate of keyboard-stepped and traditional stepped energy dissipator 3.22% and 24.33% respectively, when the flow increases from 40 m~3/h to 60 m~3/h. In total, the energy dissipation effect of the keyboard-stepped energy dissipator is better and more stable, which can provide a new idea for the actual energy dissipation engineering.