In this paper, on the basis of Preston hypothesis, kinematic principles are applied to deduce the motion relationship between tool and workpiece upon the tool's motion in planar model. From that the effect on CCOS (Computer Controlled Optical Surfacing) caused by controllable variable except dwelling time is analyzed by computer simulation. Thus, provide some reference on theory to optimize the former NC model, add a controllable variant, and realize the large departure aspherics fast manufacture, so planar motion can be applied in CCOS to converge the figure error.