The process of cutting granite material is simulated with using analysis of LS-DYNA finite element. The stress, strain and cutting force of a diamond saw blade are analyzed when cutting granite materials. Then the stress-strain distribution and cutting force curve of the diamond saw blade can be got in the process of cutting granite materials and a conclusion of the change rule of the cutting force is also obtained. When the diamond saw blade just contacts the workpiece, the cutting force rises gradually and after entering the certain cutting depth, the cutting force fluctuates in a very small range. Through the simulation, the theory of FEM model to calculate granite materials cutting force is obtained. By changing the parameters of the diamond saw blades, the influence of all parameters on cutting force of diamond saw blade is analyzed .A diamond saw blade's structure is optimized, when the parameters of saw blades is suitably selected. The processing performance of a diamond saw blade is improved further, and the result has important practical significance to process the granite material.