Abstract: The mining face in coal outcrop area, Zhaogu 2^nd Colliery, was threatened by gravel aquifer of Neogene System.Slice mining was selected in former design, but output, efficiency and economic benefit would be limited.By analyzing overlying strata damage rule with on-the-spot observation and FLAC^3D simulation and referring to full-mechanized caving and large-height mining faces with similar geological condition, selecting larger caving-to-mining ratio and fracturing-to-mining ratio to predict caving and fracturing height, applying minimum safe thickness method to selecting protective thickness, rational height of coal and rock pillar for preventing water and sand, and mining height were obtained.Results showed that only mining top-slice could free large amount shallow coal resource and improve mining ratio in thin basement area, and mining whole coal-seam with large-mining-height method in thick basement area was benefit for realizing high output and high efficiency of mine.