In view of the interfacial mechanical characteristics of steel reinforced concrete composite structure,we develop a steel casing concrete interface model with damage and slip effect.Based on the analysis of the force mechanism of reinforced concrete structure,we decompose the relative motion of steel cylinder and concrete on three dimensional scale,establish the three-dimensional constitutive relation of steel cylinder concrete interface model,choose the compressive strain of concrete as a quantitative index to characterize the damage degree of concrete,and put forward a quantitative calculation method to consider the influence of the coupling effect of local compression and slip on the load transfer performance of the interface.We carry out the compression performance test of the steel reinforced concrete composite component,and verify the applicability of the model by comparing the results of the test and the model results.