To solve the problems of RB-SiC mirrors in engineering applications, the material preparation, surface modification and aspheric processing of RB-SiC mirrors were analyzed. Firstly, according to the special modification characteristics of the RB-SiC mirrors, a new material whose thermal expansion coefficient was matched well with that of the RB-SiC was chosen to be a new support for the thermal design. Then, the modification and fabrication technologies of RB-SiC mirrors were improved based on the actual situation of the aspheric processing for better processing reliability and shorter processing cycle. Finally, the improvement were verified by experiments. The experimental results indicate that the modified RB-SiC mirror is in a good condition.The RMSs of the mirror surfaces before and after modifications have changed only 0.017λ(λ=623.8 nm,change rate in 13%),and the aspheric processing time has decreased 1 month or 2 months. The adequate margin of the 10 μm modified layer in the subsequent processing is ensured,the processing security is improved and the processing cycle of the aspheric is shortened due to the new technology,which can been applied to the preparation and processing of other aspheric SiC mirrors as well.