A sliding friction coefficient calculation model was established based on analysis of non-continuous diffusion of energy during the interfacial friction. The results indicated that the sliding friction coefficient is not related with the load and the actual contact area under elastic contact. However, when the actual contact area is close to the nominal contact area, the sliding friction coefficient will increase along with the reducing load. When sliding is slow, the friction coefficient rises slowly with the increase of the sliding velocity, and the influence is more remarkable when the sliding speed is higher. Furthermore, the larger the atomic lattice, the smaller the sliding friction coefficient is. The sliding friction coefficient increases with the rising of the atomic temperature. These results will be used to engineering application and theoretical research.