Fretting fatigue has grasped strong interest in last decades, some quantitative methods for the evaluation of fretting fatigue were developed. However, only very few studies have been reported on fretting wear, especially on its mechanical model and evaluation method. In this study, cumulative plastic strain is analyzed by FEM. To obtain accurate plastic strain, the shape change due to the plastic deformation has been taken into account. It is found that the cumulative plastic strain will be saturated after several hundred cycles at the initial fretting stage. Considering that fretting wear is very small during this early stage, as it can be observed from the fretting test, the wear at the contact interface before the saturation of cumulative plastic strain can be neglected. Since the saturated cumulative plastic deformation represents the stable deformation of the contact interface, it is proposed that the fretting wear can be characterized by the saturated cumulative plastic strain and accumulative shear stress. With this method, the wear profile of the specimen is predicted. By comparing FEM results with the experimental results of fretting wear, the proposed wear formulation is validated.