In grinding and polishing of the aspherical and freeform surface, the CCOS technology is widely used. It commonly uses constant pressure during polishing, and thus the desired amount of material to be remove depends on the dwell time. This paper focuses on the variable pressure CCOS polishing technology. It adds one more degree of freedom to the polishing process, in which the desired amount of material to be removed is controlled by both the polishing pressure and the dwell time. Firstly, a mathematical model was established for the variable pressure polishing process. Then, the stability and response speed of the output force of the polishing tool, and the stability of removal function was measured and analyzed. Finally, a material removal experiment that applied sinusoidal force was carried out on a K9 material mirror. Results show that frequency of the measured force is the same as that of the ideal sinusoidal polishing force, with a standard deviation of the force error being about 0.35 N. Its effect on PV and RMS of the finish surface is less than 9%. The spatial period of the measured surface profile is the same as that of surface profile obtained by simulation of the sinusoidal polishing process. The surface profile error is within 17%. In this paper, variable pressure polishing was achieved, and its effectiveness for optical processing was verified.