Abstract: The finite element simulation of friction and wear experiment on TIN film / carbon steel substrate system shows that several stress concentrations at edge of grinding 一trace , tensile stress inside and outside grinding - trace , shear stress at film / substrate interface all affect tribological behavior of the system The results calculated by FEM have been confirmed by pin / disc test According to the analysis of crack initiation and propagation in film as well as damage and breakage of system , the process of friction and wear can be divided into several stages , such as wear -in , steady wear , film unsteady wear , and system failure The failure mechanism of hard film / soft substrate system in friction and wear experiment under small loading has been suggested The stress concentrations and tensile stress have important function on crack initiation and propagation , which can cause the brittle breakage in film The stress concentrations at edge of grinding -trace due to deformation play most important role on early damage which results in wear failure of film / substrate system