Abstract: The linear elastic model is mostly adopted for analysis in the numerical manifold method, but the nonlinear model is scarcely studied. Based on the characteristics of the numerical manifold method and constitutive models of rock and soil mass, the formula of numerical manifold method for nonlinear analysis is presented. The elastic modulus of Duncan-Chang model is modified to describe the nonlinear relationship by use of the midpoint incremental method, in fact, the subsection linear ralationship is substituted for the nonlinear ralationship. Finally, the validity of nonlinear analysis for rock and soil mass is proved.