Abstract: In order to solve the problems of blocking the head unload point of conveyor head and the entrance of the reload machine, a large coal crushing device in fully mechanized coal face is put forward.The main motive force comes from the emulsion pumping station of the fully mechanized coal face, which is driven by the telescopic cylinder, the angle regulating oil cylinder, the vertical lifting oil cylinder and the hydraulic motor.Through the hydraulic control system to control the action of each cylinder, the multi degree of freedom motion of the large coal crushing device is realized.The field test shows that the device is simple in operation and good in equipment reliability.It basically solves the problem of blockage caused by large coal blocks, and has no influence on the normal operation of other equipment, improves the production efficiency of the working face, and has a remarkable economic benefit.It has good practicability and a great prospect of popularization and application.