Abstract: To analyze the influences of swinging motion parameters on lapping and polishing trajectory in plan lapping and polishing with swinging motion, a model on movement trajectory is established, and the quantitative evaluation method of trajectory non-uniformity is used. The results show that the swinging amplitude and the swinging angle have an obvious influence on the trajectory non-uniformity, while the swinging angular velocity has little effect on trajectory non-uniformity except that the swinging angular frequency takes a special value. The trajectory non-uniformity can be well improved when the swinging amplitude is 15 mm and the swinging angle is 30°, whose value can be reduced to 0.058. If the values of the eccentricity and swinging motion parameters are improperly selected, the value of trajectory non-uniformity can be up to 0.284.