In grinding and polishing of the aspherical and freeform surface, the CCOS technology is widely used. It is a process during which errors can be corrected quantificationally by a small tool that can follow the local curves of the aspherical and freeform surface. It commonly uses constant pressure during polishing, and thus the desired amount of material to be remove depends on the dwell time. This thesis the pressure regulation is introduced into the CCOS polishing system. The pressure can be controlled in real time in the process of processing, and the application of pressure control in CCOS polishing is realized. The main characteristic of this technology is that 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 machining efficiency and the influence of pressure error on machining quality are simulated and analyzed. Finally, a material removal experiment that applied sinusoidal pressure was carried out on a K9 material mirror. Results showed that frequency of the measured pressure is the same as that of the ideal sinusoidal polishing pressure. 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 thesis, variable pressure polishing was achieved. Compared with the constant pressure CCOS polishing technology, the variable pressure CCOS polishing technology adds one more degree of freedom to the polishing process. It need have higher requirements for the pressure active control system, such as the output pressure range, response speed and precision. These performance parameters can affect the processing results. Therefore the key to developing the variable pressure CCOS polishing technology is to research the polishing tool, which must have high performance pressure active control system.