Abstract: For the safe mining of coal resource, depending on the designing mining height, a mine applied the two methods of empirical formula and numerical simulation to study the height of water flowing fractured zone of 16^# and 17^# coal seams which are exploited alone. The result shows that these two values are 36.1 m and 29.7 m according to the empirical formula, and 37.1 m and 26.9 m according to computer simulation. Depending on the designing mining height, the height of water flowing fractured zone of 16^# and 17^# coal seams after mining is 41.7 m according to computer simulation.