Abstract：Rock mass contains large-scale deficiencies，such as pores，fissures and faults，which are usually referred to rock defects. Faults，cracks and fissures are called high-level defects，micro-cracks, pores are called low-level defects. Rock defects of rock deformation and the damage control will have close relationship with different fissure scales. The relationship of quantity and scale of rock mass fissure is analyzed，including great crack and microcosmic fissure. Then with numerical simulation，it is found that the fractures of rock samples will increase gradually；and the control effects from microcosmic fracture scale to deformation and the rock mass failure are studied. The result indicates that the arrangement defect controls the deformation，stability and rock mass failure when the scales of crack，fissure，cavity，spacing，hole are coexisting in rock masses.
