The finite element method mainly is used in the research. The correctness of the calculation model and method is verified based on the contact patch that contained in the test. Then the influence on wheel-rail contact characteristics of tread wear is studied. First of all, the tread profile coordinate data of wheelset is obtained through the actual test. finite element model is established according to the data. Shapes and sizes of contact patch when the wheelset is free are obtained in the test. Compared with the contact patch that be obtained in the Finite Element Simulation, the correctness of finite element model and contact parameters is verified. Based on this finite element model, the regular that effects on contact stress and the wheel-rail contact patch of changing tread with the increase in vehicle running mileage is studied The results show that with the increase of wear, profile of wheel and rail become more matching, contact stress decreases gradually, the wear rate also decreased gradually; however, when the wheel wear developed to a certain degree, the contact stress and wear rate increases quickly.