Abstract: In this paper, simulation study was carried out on the law of the overburden strata caving and the support deformation under the conditions of different thickness and pitch of the coal seams and lithological characters of the roof rock by taking the pitching oblique fully-mechanized mining of the steep thin seam in Fengchun Mine as the engineering background and using 3DEC discrete element numerical simulation method. The numerical analysis results showed that when the coal seam thickness was smaller, the roof was more broken or the seam pitch was smaller, the vertical stress, the vertical displacement and the unloading arch height of the stope roof along dip direction of the coal face were all larger, on the contrary, they were smaller; the yield load of the powered support was the largest in the middle part of the working face, the second in the upper part and the smallest in the lower part. Based on the numerical simulation results, corresponding powered support was developed and then applied in the engineering, the test results showed that the error between the numerical simulation results and the measured results of the support yield load was within 5.0%, indicating that the powered support had better adaptability in the pitching oblique coal face of the steep thin seam.