The wok aims to verify effectiveness of processing of sapphire with bonded large particle size (>30 μm) SiO2 grain bonded abrasive tool, optimize abrasive tool formulas and provide effective reference for high efficiency, high quality and low cost processing of sapphire wafer. With magnesium oxychloride cement as binder, bonded SiO2 grain bonded abrasive tools with different formulas were fabricated to process sapphire. Removal rate and surface quality were taken as evaluation indices to study the effects of particle size, binder proportion and grain percentage on processing effects. The sapphire was processed by six kinds of SiO2 grain bonded abrasive tools of different particle sizes (all >30 μm). Surface roughness was improved. The smaller the particle size was, the better the improvement effect was. The removal rate and roughness were influenced by the mole ratio of active MgO, MgCl2 and H2O. The higher the abrasive grain content was, the higher removal rate was, and the smaller surface quality was. In the magnesium oxychloride binder, the molar ratio of active MgO:MgCl2:H2O was 7:1:16; 325# SiO2 was used as abrasives, and the grain mass accounted for 60% of the binder mass. Abrasive tool is made to process sapphire with revolving speed of 210 r/min, load of 0.4 MPa, processing duration of 3 h. The average removal rate is 17 μm/h, and the surface roughness Ra increases from initial average 345 nm to average 9 nm.