Abstract: Based on the occurrence characteristics of coal seam at Bulianta Coal Mine 12407 working face, the 2D geological model for different mining height was established by using UDEC software, and we analyzed the development laws of water flowing fracture zone through key stratum. The results show that key stratum has a larger effect on the development law of water flowing fracture zone; the development height of water flowing fracture zone and mining height are positive correlation; the average ratio of height of water flowing fracture zone and mining height is 18.7, which explains the development of higher water flowing fracture zone. The research on development law of water flowing fracture zone in Bulianta Mining Area can forecast damage degree of the overlying rock in different mining height in the mined-out area, and we can take measures to prevent sand inrush and water inrush at working face and protect plants on the surface.