Abstract:Microstructure and cell of rock are researched by means of SEM. The propagation of rock microcrack is analyzed. The fractal characteristics are analyzed by dissipated energy consumed by microstructure fracture. The form and direction of crack propagation in rock are obtained according to given loading,by use of fractal geometry method and micro-thought method. The regularity of damage evolution of rock is explained. It is shown that the speed,direction and quantity of microcrack propagation depend mainly on the component,combination of mineral,combinatorial density,quantity and direction of load,state of stress,and ratio of stress components.