The mechanical properties of metamorphic rocks are affected by the existence of foliation, which induces apparent anisotropy and heterogeneity. This study performed a series of pull-off and direct shear tests to investigate the tensile strength, peak, and residual shear strength of schist foliation. Finally, the effect of grout reinforcement on fractured foliation was evaluated. The key findings include: (1) A nonlinear failure criterion for foliation was adopted to reasonably describe the failure envelope of schist; (2) Considering the grout reinforcement on fractured foliation, the strength of grouted schists significantly increased. The high roughness strongly contributes to the grout reinforcement on the schist foliation; (3) The severely fractured specimen with a rough surface reflects both material and interface failures, while the specimen with a low roughness exhibits interface failure.