On the basis of the potential barrier of contact surfaces and the stochastic properties of contact surface morphology,a new calculation model of sliding friction force loaded on nano-scale rough surface is established.Then,the model is used to numerically calculate the sliding friction force of the same material friction pair with rig- orous stationary process.The results show that the normal load is linear to the mean sliding friction force obtained by the presented model and is exponential to the average surface separation; and that the average normal force in- creases linearly with the standard deviation of roughness height distribution at the same average surface separation.In addition,the calculation results are consistent with the existing research conclusions,which means that the pres- ented model is effective and feasible.With this model,the mean sliding friction force can be predicted according to the distribution parameters of contact interface morphology,material parameters and normal load.