Abstract: This paper is focusing on the problem of tangential contact damping to study when two rough surfaces contact under combined normal force and tangential force. Firstly, according to the KE model, the tangential contact behaviors of a single asperity in the elastic, elastic-plastic, and plastic deformation stages were analyzed, and then the stick-slip characteristics of asperity in the three deformation stages can be obtained. Secondly, according to GW statistical model, a statistical model of a mechanical interface tangential damping was built based on a type of “asperity-based” model of including asperity elastic, elastic-plastic and plastic deformation mechanism, which considered the asperity stick-slip tribology behavior in the three different deformation mechanisms. Finally, the effects of the normal preload of mechanical interface, vibrational frequency and tangential dynamic displacement amplitude on the mechanical interface tangential damping were respectively discussed. These conclusions can be obtained that: the tangential contact damping coefficient increases with the increase of the normal load on the mechanical interface, whereas decreases as the tangential excitation frequency and the tangential dynamic displacement amplitude increase. For the high frequency and bigger amplitude, the tangential contact damping coefficient of joint surface is almost independent of tangential relative displacement amplitude and vibration frequency. In order to verify the veracity of the proposed model, a tangential damping experiment of joint surface was established under a dynamic tangential force, and the results show that the simulation results of the proposed theoretical model are mainly consistent with the experimental results in the change rule and the order of magnitude, which proves that the tangential damping of the proposed model is correct and effective.