The work aims to study effects of slurry PH, temperature and concentration on removal rate of sapphire material to improve polishing efficiency. Chemical mechanical polishing (CMP) for C-plane sapphire wafer with diameter of 50.8 mm was performed by using CP-4 single-sided tester. The removal rate of material during sapphire polishing was analyzed by using electronic analytical balance. Surface topography and roughness (Ra) were both evaluated with atomic force microscopy (AFM). The effect of different SiO2 slurry (different pH, temperature and concentration) on the material removal rate (MRR) was investigated. MRR first increased and then decreased as slurry pH (10.4 to 12.2) and temperature (20 ℃ to 45 ℃) increased. The MRR and Ra were 1.119 μm/h and 0.101 nm respectively provided with KOH adjusted pH of 12.2, water-bath heating slurry temperature of 35 ℃ and volume ratio of original slurry: DI water of 1:1. Chemical effect is enhanced and mechanical effect is weakened as pH increases. Equilibrium point and optimal MRR are available when the pH value is 12.2; chemical effect is enhanced and mechanical effect remains unchanged as the temperature increases. The two effects achieve a balance and optimal MRR is available at the slurry temperature of 35～40 ℃. Concentration of the slurry increases significantly if the temperature exceeds 40 ℃. Too high concentration may lead to decrease of MRR; MRR of the sapphire subject to chemico-mechanical polishing increased by 71.4% af-ter relevant properties of the slurry have been optimized.