Abstract: It is very important to study the height and shape of overburden failure for safety mining under water body. According to the engineering geological data and mine exploration of S2S9 working face in Daping Coal Mine, we propose the σ₁>σ_t as a criterion of studying water-flowing fractured zone, using ADINA finite element software to simulate the coal mining process, analyze failure characteristics of overburden rock and water flowing fractured zone under the action of mining and seepage and carry on the inversion calculation with field example. The water flowing fractured zone height of numerical simulation is 160 m, which is consistent with the measured data and provides a feasible method to determine height of the water flowing fractured.