Abstract: Aim to reveal development characteristics of water flowing fracture during mining under extra thickness Luohe aquifer in mining thick coal seam in Tingnan coal mine, the law of development characteristics of water flowing fracture with different mining height. Results showed that measured value of water flowing fracture in NO.204 working face was 144.0m with mining height 6 meters, which was 140.2 m with mining height 7.5 meters in NO.206 working face, and 148.3 m with mining height 9.0 meters. The water flowing fracture developed near the bottom of Yijun aquifer, but not directly destroyed Luohe aquifer. The water flowing fracture did not increase linearly with the increase of mining height, but controlled by the location of key stratum in overburden. Measured results also verify that the discriminant method based on theory is correct and its applicability in Tingnan coal mine. The value of water inflow in NO.204, NO.205, NO.206 working faces also did not increase linearly with the increase of mining height also verified that the water flowing fracture did not directly destroyed Luohe aquifer. According to this research, the max mining height of working face could increase to 14 m theoretically and the coal recovery rate can be appropriately increased. The research results can provide reasonable design of mining height and roof water prevention for the mining of other panel in Tingnan coal mine.