Abstract: Based on the generalized potential theory,an elasto-plastic model of multi-potential surface for interface was created.In the model,the soil-structure interface problem was regarded as two-dimensional question in(σn,τ) field,and the vector composed by the plastic strain increment of dε np and dγ p was represented by gradient vectors of two linearly independent potential functions σn and τ,and the plastic state equations were used to replace the traditional field surface.The model parameters could be obtained by uniaxial compression tests and simple shear tests.The method was introduced,and using the parabola and damped exponential curves to simulate the dilatancy of interface,in which the parameters with definite physical meanings and the fitting results with high quality.It was shown that the model,based on a legible mathematical theory and a small quantity of physical hypothesis,could reflect the dilatancy of interface and well simulate the deformation characteristics of interface.