Abstract: For the phenomenon of roof falling and rib spalling under the condition that the stability of end-face roof and rib is significantly reduced in top coal because of low intensity and coal mining fractured joints in large mining height mining practice, we analyzed the reasons for the end-face roof falling accident and spalling, and simulate the influence of different coal cutting height on stress and deformation of end-face in fully mechanized caving face in mining process by UDEC numerical simulation technology, and found the best mining height. Theoretical analysis and field practice observation shows that the height of most severely damaged is 5.5 m under the condition of 6.0 m thick coal.