Abstract: The finite element simulation for scratching test showed that undulant variation of shear stress , difference of shear stress at interface of film / substrate , surface tensile stress around contact region , several concentrations under high loading etc . played important roles on failure of film / substrate . The difference of shear stress between film and substrate near interface , which was calculated by the FEM simulation at critical load of scratching test , could be used as a criterion for estimating adhesive strength . Two mechanisms of failure of film / substrate system in scratching test have been suggested . The validity of the FEM simulation has been confirmed by the result of scratching test to TiN film deposited on different substrate . The critical load resulted from synthetic effect of film / substrate system performance , such as adhesion strength , load bearing capacity , cohesion strength . The limitation of estimating adhesive strength of film / substrate by critical load in scratching test further proved by results of friction and wear test in reciprocating sliding under low loading .