The surface waviness model of races in linear motion ball guide was developed on the basis of the test, and the analytical model of contact amount changes caused by the surface waviness was established. Based on the Hertz contact theory, the relationship between the contact amount and contact force between the ball and the race was studied. The slider was simplified as a rigid body, and the dynamic equations of slider were established. The equations were solved under a certain speed of slider, and after the comparison with the experimental results, the validity of the dynamic model was verified. The results of numerical calculation show that the surface waviness of races should not be ignored in the vibration study of guide system.