Based on CCOS and Preston assumption, a grind-polishing technique for rotational symmetry aspheric surface polishing process is proposed. In order to achieve equal-remove rate, a variable speed motion model is established based on keeping the contact pressure between grinding tool and workpiece as a constant. By this theoretical principle, the functions of rotate speed and feed speed for every processing position have been inferred. To solve these functions, the rotation speed of workpiece and feed speed of grind-polish wheel in different working position should be gotten. CNC equipment would execute processing accurately. The results of experiment prove that the motion control model could ensure precision of grinding process, so that, the difficulty of polishing process has been reduced and whole processing efficiency has been improved.