Use multi-mode optimization technique to improve material remove efficiency and precision. Introduced principal theory and mathematical model of multi-mode optimization technique. Compared with traditional computer controlled optical surfacing (CCOS) technique, we introduce the advantage of multi-mode technique. In the last, we grind a SiC mirror using multi-mode technique. Take SiC mirror with caliber of 2040 mm as an example to introduce how the multi-mode technique applied in grind large aspheric SiC mirror. After a complete multi-mode process, peak valley (PV) of the surface converges from 8.72 μm to 4.91 μm and root mean square (RMS) of the surface converges from 0.91 μm to 0.52 μm， which demonstrates the validity of the multi-mode technique.