Abstract: In order to have the coal and rock falling down law of the high cutting fully mechanized top coal caving mining in thick seam, the improved discontinuous deformation numerical simulations DDA software was applied to study the stress field and the coal and rock migration law of the high cutting fully mechanized top coal C aving mining at different mining stages.The results showed that with the mining operation of the coal mining face, the round stress filed surrounded the coal mining face would steadily change to be an elliptical stress field.There would be three obvious zones and they were a stress released zone, a stress increased zone and a transit zo ne between the above zones.Meanwhile, the horizontal displacement varied with the time would be complicated and the vertical displacement variation would have a ce rtain law.With the vertical displacement variation, the overburden strata could be divided into three zones and the overburden strata and top coal migration law of the hi gh cutting fully mechanized top coal caving mining face could be obtained.