In order to solve the problem that the tunnel crosses the water-rich fault fracture zone, the construction risk is large, and the problems of surrounding rock instability and water inrush are very likely to occur. Based on the engineering background of the Xiaocaoba tunnel of the Chongqing-Kunming high-speed railway crossing the water-rich fault fracture zone, the fluid-structure interaction numerical model was established by using FLAC^3D to study whether to consider the influence of groundwater action, different grouting forms, grouting ring thickness and the force of the supporting structure under the influence of groundwater. The results show that the stability of the surrounding rock is poor under the consideration of groundwater, and after the tunnel excavation, the groundwater is distributed in a "funnel-shaped" manner around the tunnel after the seepage reaches a steady state, and the stability of the surrounding rock is enhanced after the advanced grouting reinforcement, and the grouting reinforcement form of the whole perimeter is better than that of the grouting around the arch wall. On the basis of selecting the grouting form, the parameters of the grouting ring were continuously optimized, and it was concluded that with the increase of the ratio of grouting ring thickness and permeability coefficient, it can effectively reduce the displacement of surrounding rock, limit the development of plastic zone, and reduce the pore water pressure of the primary branch, and the increase of the thickness of the grouting ring can significantly change the distribution range of the pore water pressure of the primary branch. After the construction of the appropriate grouting scheme on site, the feasibility of the grouting scheme and the rationality of the selection of grouting parameters were verified by comparing the monitoring values around the tunnel with the simulated values, and the stability of the surrounding rock was effectively controlled. The research results can provide reference value for the design and construction of similar tunnel projects in the future.