Abstract: Based on the transferring rock beam theory, it is pointed out that the cyclic fracturing length and the cyclic weighting interval of the rock beam fracture are two different parameters. The mechanical parameters, rock beam structure and mechanical properties affect the cyclic fracturing length, and besides the cyclic weighting interval, other engineering parameters such as the strength of working face support and the advancing speed can influence the fracturing of rock beam structure. According to structural mechanics of cyclic fracturing length and the cyclic weighting interval for the rock beam fracture, Mechanical models and the motion equation are established. The motion equation has been proved to be sound and feasible in practical application.