Abstract: Based on generalized nonlinear strength theory that has been proposed by author, combined with mechanics characteristics of rock materials, a generalized nonlinear strength theory for rock is proposed. The failure function of the theory is a smooth curve between SMP criterion and Mises criterion in the π plane and is a exponential curve in the meridian plane. The generalized nonlinear strength theory for rock is validated by the triaxial compression test data for different rocks that have been published. The generalized nonlinear strength theory for rocks can be widely applied to all kind of rocks and can describe the characteristics of nonlinear strength in the π plane and the meridian plane. Compared with the Hoek-Brown criterion using test results of five different rock types under the three-dimensional stress states, the superiority of the nonlinear strength theory for rock materials has been embodied in this paper.