In the area of astronomy and space camera, the application of silicon carbide (SiC) will have a good future for its specific stiffness and quickly thermal diffusion. However, SiC as a new material of optical mirror is difficult to process efficiently because of its specific characteristics such as stiffness and material structure. To manufacture the aspheric SiC

mirrors of a R-C system with aperture 520mm in diameter, we starts to research on optical surfacing of SiC. Some small SiC parts are used to do serial surfacing experiments for finding a technology to improve the surface roughness of SiC. Test result shows that the surface roughness (RMS) of the best plate is better than 1.0nm. Finally, the surfacing results of the ellipsoid primary mirror with aperture 520mm in diameter and the hyperboloid secondary mirror with aperture 114mm in diameter of the R-C system are measured. The surface error (RMS) of them is less than 15nm, and the surface roughness of them is better than 1.8nm. The results meet the requirements of optical mirrors.