The DF8B locomotive is a main trunk freight transportation diesel locomotive and can be used to study the causes of locomotive wheel tread damage. Based on vehicle dynamics and the Hertz nonlinear contact theory, we tested the locomotive dynamic responses on the harsh lines. Frequency domain analysis was used to obtain the amplitude and frequency characteristics of major components, such as the wheel and car body. The experimental results showed that the longitudinal shock absorber has a great relationship for wheel tread damage. One of the main reasons for wheel polygonization was the torsional vibration of the locomotive wheel. Although the wheel polygonization was very serious, but it doesn′t peel.