Firstly, the shear element stiffness matrix of contact surface for reinforced soil-structure was analyzed, the failure characteristics of shear stress were considered, the Mohr-Coulomb strength criterion was considered to measure microcosmic element strength of reinforced soil, and a statistical damage constitutive model for the simulating process of reinforced soil slipping deformation was established. Secondly, on the basis of this, a comprehensive approach to determine model parameters was proposed, and this model has fewer parameters and explicit physical meanings. Finally, the theoretical result of this paper was compared with the conventional direct shear tests. It has been indicated that this model can simulate the characteristics of the slipping deformation of reinforced soil, and can reflect the law of shear strength with normal stress. It has been shown that the method proposed is rational and feasible.