Abstract: In order to increase top coal recovery ratio of extra-thick coal seam, we analyze the impact of drawing interval on top coal recovery ratio based on the complicated geological conditions of extra-thick coal seam with large dip angle on Danshuigou coal mine. It is found that top coal recovery ratio of “Two Wining and One Caving” technique is the highest and refuse rate the lowest in the three techniques. Top coal recovery ratios in different ways of top coal drawing of extra-thick coal seam with large dip angle are studied by numerical software PFC, we identify that the “Two Wining and One Caving”with top coal drawing ways of two-times order caving and drawing interval of 1.6 m is the reasonable coal caving technology. Industrial test indicates that optimized caving technology can significantly improve top coal recovery ratio which reaches to 87.62% and recovery ratio which reaches to 87.12%.

Key words: large dip angle, extra-thick coal seam, drawing interval, way of top coal drawing