Abstract: Abstract: According to the problems of collapse of top-coal and coal wall spalling in fully-mechanized caving mining with large mining height, the influence of coal cutting height to coal recovery cofficient and rib spalling was studied by theoretical analysis, numerical simulation, technical and economic comprehensive comparison and analysis.Through establishing the rib spalling compression-shear mechanical model of fully-mechanized caving mining face with large mining height, the rib spalling mechanism was analyzed, and the reasons that fully-mechanized caving mining face with large mining height more easily coming up rib spalling than large mining heigh t fully-mechanized face in the same cutting height were studied.Increasing the active support reaction from hydraulic support to the top-coal and selecting the reasonabl e hydraulic support structure can enhance the top-coal caving and reduce rib spaling probability at the same time .Comprehensive analyzing the influence of difference coal cutting height to coal recovery rate, rib spalling control, engineering and equipment investment, the biggest coal cuting height was confirmed by 4. 5 m in fully-mec hanized caving mining face with large mining height of Guanzigou Mine.The two column cover type caving hydraulic support of ZFY12000/26/47 worked well in Guanzig ou Mine.