Abstract: In order to get reasonable technical parameters for the slicing top-coal caving face in ultra thick coal seam of Huating coal mine, through the theoretical calculation with comprehensively considering of the balanced production and the caving broken space of top-coal and the reasonable mining-caving ratio, the paper obt ained the layer thickness was 13.2 m, mining height of fully mechanized mining was 3.3 m, the caving height was 9.9 m, the mining-caving ratio was 1 : 3.The particle fl ow numerical simulation were applied to analysis and determination the technical parameters of caving once with mining twice and two wheel giving-out coal of single s upport of the first layer in order. The authors analyzed the extraction rate of the mining face finally, the top-coal caving-out rate reached to 81.45%, the mining face extra ction rate reached to 84.48%.