This paper takes geological conditions of the Li—Jun expressway by Kang JiaGou and Tong De coal mine goaf as prototype, using the simulation experiment of similar material, simulates the formation process and distribution of the mined rock fracture and the damage variable of the mined rock by using the simulation experiment of similar material, At the same time, It researches the evolvement law of rock’s fracture network in caving zone, fractured zone over goaf using fractal geometry theory. It analyses the damage variable law in caving zone, fractured zone using the damage mechanical theory, and found the relationship of damage variable and mined width. The conclusion of the experiment indicates: with the advance of the working surface, the fractal dimension of the mined rock crack goes through small → large →small, and stable process of change. In the identical push distance of the working surface, fractal dimension of caving zone is 1.0—1.2 times of fractured zone. With the advance of the working surface, damage variable increases gradually, under the identical mined width, damage variable of caving zone is greater than fracture zone, caving zone is about 1.04—1.11 times of fracture zone. Damage variable of goaf central zone is greater than edge.