To explore the mechanical behaviors of surrounding rock-grouting ring-lining system in deep tunnel under non-linear seepage condition, Izbash non-linear seepage model was introduced and the hydraulic head distribution of surrounding rock-grouting ring-lining system was given. Based on the unified strength theory and considering the possible location of plastic zone, the displacement, stress, and radius of surrounding rock plastic zone under grouting and lining support were deduced theoretically. Theoretical results and numerical solutions were compared through an example and feasibility of the theoretical method was verified. The engineering significance for the supporting design of mountain tunnel with rich water considering non-linear seepage was further discussed. Results show that the influence of non-linear seepage on elastoplastic mechanical effect of tunnel was mainly reflected in the hydraulic gradient coefficient m₁ of surrounding rock. In the process of the transition from low-speed non-linear seepage to high-speed non-linear seepage, the radius and displacement of plastic zone became larger, and the stress of surrounding rock decreased. The thickness design of grouting ring and lining support should be considered from the perspective of non-linear seepage of surrounding rock. The research results provide a theoretical basis for the support design of non-linear seepage tunnel.