Abstract: In this paper, based on a series of simple shear tests, the shear failure and deformation character at interface are analyzed and investigated. The idea of sliding deformation and shear deformation at interface is distinguished, and the sliding zone at interface is defined. A new interface model is established in this paper. Furthermore, the method of determining parameters of this model is proposed. Calculated results show that the new model can reflect shear stress and relative deformation at interface reasonably. It is superior to the conventional interface models.