Abstract: The paper discusses constitutive models of geologic discontinuities(e.g.joint and fault etc.)in engineering geology within the theoretical framework of the elastoplastic damge.These models can reflect the behaviours of damage softening,elastic stiffness degradation and shear dilatancy.In the models,the plastic deformation increment is non-normal to the yield surface,but the obtained constitutive matrix is symmetrical.The former is consistent with experimental data and the latter is extremely important in the numerical analysis and theoritical research.