In order to reveal the hydraulic characteristics along the water diversion tunnel of swirling shaft under ultra-high water head, the effects of different inlet and outlet forms on the swirling state of water flow and wall pressure distribution were studied by physical model test and numerical simulation. The results show that the swirling shaft used in this project can form a stable cavity under various working conditions, and the energy dissipation rate of the shaft can reach more than 86.2%, and the energy dissipation is sufficient. After the inlet width of the shaft vortex chamber is narrowed, the swirling velocity can be increased to a certain extent. However, under the check condition, the hydraulic jump position at the junction of the end of the slope section of the upper tunnel and the side wall of the vortex chamber moves up to the slope section of the upper tunnel, that is, the water flow has a phenomenon of water flowing upstream, and the water flow in the vortex chamber will climb more obviously. After the bottom plate of the stilling well is reduced by 5 m, the flow pattern in the stilling well is improved. According to the flow pattern of the stilling well and the safety of the bottom of the hole, it is recommended to use the optimization scheme of reducing the bottom plate by 5 m.