To achieve a high-quality quartz glass substrate and to improve the performance of photomask equipment, a Chemical Mechanical Grinding (CMG) method for the quartz glass is developed. By actively enhancing the chemical reactions of the workpiece and the abrasive grain, bond and the grinding fluid and dynamically balancing the chemical reaction and mechanical remove,the process method can avoid the sub-surface damage caused by eliminating the brittle material to achieve high surface quality and high shape precision processing of a large-diameter glass workpiece. For the processing characteristics of CMG for the quartz glass, this paper develops the CMG-specific wheel and grinding fluid. Then it uses orthogonal experiment method to optimize the CMG process parameters for the quartz glass, and analyzes the effects of the grinding pressure, wheel speed, grinding fluid traffic, pH value and other factors on the surface roughness and processing efficiency in CMG processing.On the basis of the optimized processing parameters, it obtains the surface roughness of quartz glass in 0.795 nm. Obtained results show that the finished substrates have the same optical performance with the substrates processed by Chemical Mechanical Polishing(CMP), and the performance can meet the needs of photomask equipment.