Based on analysis of Chemo-mechanical-grinding(CMG) technology with Soft Abrasive Grinding Wheel(SAGW), cup-type SAGWs with Fe2O3 and MgO as the main material were respectively developed. The contrast grinding process with the developed two kinds of SAGWs was applied to nano-precision finishing for optical surface of silicon(Ф150 mm) and machining parameters were optimal selected. Contrastive analysis of CMG, diamond wheel grinding and Chemical Mechanical Polishing(CMP) for mirror were carried out. The surface and sub-surface damaged by CMG with SAGW were detected and analyzed. The results indicated that the grinding performance of MgO SAGW were stable. Good form precision and surface roughness were obtained. Measurement of CMG mirror from 3D surface profiler(0.568 nm RMS) or atomic force microscope(0.554 nm Rq) was reached to the roughness of CMP mirror. Sub-surface Damage Depth(SDD) by angle polishing method was detected, which was close to zero.