New mirror grinding principle was proposed for SiC ceramics in connection with grit protrusion parameters derived from diamond grinding wheel, including active girt number and grit edge angle. In grinding, wheel moving direction is vertical to cutting direction different from traditional plunge and traverse grinding and dressing + iron-truing was also employed to protrude and truncate grit cutting edges. First, formation of ground mirror surface was theoretically analyzed concerning wheel topography parameters and grinding parameters. Then, dressing experiment and iron-truing experiment were carried out respectively to investigate ductile-mode mirror grinding behavior. Finally, mirror grinding experiment SiC ceramics was realized on 20 mm x 50 mm ground surface. Theoretical analysis showed that grit cutting depth and surface roughness depend on wheel rotating speed, wheel moving speed, grit cutting edge number and grit cutting edge angle, no depending on the depth of cut. Experimental results showed that ground mirror surface can be obtained by improving grit protrusion feature and decreasing wheel moving speed.