Abstract: To improve the caving condition of high toughness coal seam in fully-mechanized mining, the mechanism of difficult caving was analyzed through theoretical analysis based on the experiment of physical and mechanical parameters of the coal samples. Simulation of the top coal caving condition was done before and after the softening and the distribution of abutment pressure was tested through similar material simulation test. It shows that the elastic modulus of high toughness coal seam is smaller than the roof. The deformation of the coal seam is larger than the roof, which leads that underground pressure can not be well passed to the top coal. Top coal is hard to cave and broken, hanging arc is formed and the caving condition is serious. After softening the top coal, caving condition is obviously improved, the immediate roof can be caved with the pace of mining and filling the gob area. The position of stress peaks in the top coal moved deep to the front of coal wall. The peak stress position of top coal in the front of coal wall obviously transfer to deep position, and the top coal above and behind supports was well released which was benefit to cave coal.