In order to characterize the relationship between the surrounding rock and support structure under the constraint system of swelling support structure, starting from the swelling problem of argillaceous slate, the swelling test, indoor tunnel scale-down physical model test and numerical simulation were utilized to analyze the interaction process between the surrounding rock and supporting structure in argillaceous slate tunnel in water-rich environment, and the mutual feeding model of the swelling and supporting structure of the surrounding rock of argillaceous slate tunnel in water-rich environment was constructed. The results show that: There is a strong positive correlation between the peak swelling stress, strain of argillaceous slate and the free saturated water absorption rate in the water-rich environment. Based on the relationship between the deformation of surrounding rock, supporting structure, tunnel displacement and swelling stress, the ultimate deformation of the tunnel is predicted according to the peak swelling force of the surrounding rock. The interaction between surrounding rock and supporting structure of swelling rock tunnel is a long-term "mutual feeding" process, which reflects the relationship of "promotion and inhibition" between surrounding rock and supporting structure. The swelling of surrounding rock promotes the deformation of the supporting structure, and the supporting structure in turn inhibits the deformation of the surrounding rock. The research results can provide reference for the design and construction of swelling rock tunnel.