Abstract: The water-flowing fractured zone development height in under slicing mining of contiguous seams is studied in Luxi Coal Mine by the means of numerical simulation and field measurement. The results show that by the analysis of FLAC^3D numerical simulation, the thickness of upper slicing is 2.3 m, the height of water-flowing fractured zone is 33.6 m and thickness of lower slicing is 3.42 m,the fracture height is 39.4 m.Field measurement shows that water-flowing fractured zone development height is 41.51 m after lower slicing mining, the increasing amount of water-flowing fractured zone is less, and water-flowing fractured zone of upper slicing is 4.33 m, which is less than before. Mining fissure closes partially especially the upper micro-fractures, so water-flowing fractured zone development height is lower than before.