Abstract: Based on the long-wall full-mechanized mining on strike of steep thick coal seam at the 44407 work face of Wangjiashan Coal Mine in Gansu province and using similar material simulation experiment and numerical simulation to analyze the activity phenomenon of the stope wall rock,and to summarize the laws as below: coal collapse along the strike is divided into four stages as top coal primary caving stage,top coal large area caving stage,immediate roof caving stage and basic roof caving stage.Ground pressure along the coal seam is greater at the middle and upper layer than in the lower layer while coal rock collapses in the upper layer is more than in the lower layer.At the middle and upper section of large inclined full-mechanized work face,special attention must be paid to stability of hydraulic powered supports and slip prevention measures while preventing the rib spalling and roof-falling in front of the powered supports.