Abstract: To address the complex developmental mechanisms of water-conducting fracture zones in overlying strata induced by repeated mining of ultra-thick coal seams, we investigate the Liuhuanggou Mine through integrated rock mechanics testing, key stratum identification, and overlying rock strata structures analysis.Three distinctive failure modes of key strata under repeated mining conditions are established: single-seam dominant mode, downward mining interactive key stratum mode, and upward mining interactive key stratum mode.A novel height prediction methodology for water-conducting fractures is proposed based on the spatial positioning of overlying key strata during repeated extraction of ultra-thick coal seams.Key findings reveal: Significant vertical variations in quantity and positioning of key strata when mining coal seams 4-5 and 9-15,with horizontal heterogeneity characteristics.Successful application of the proposed prediction methodology to estimate fracture heights in boreholes across the mining area.Close alignment between theoretical predictions(306.1 m at borehole 27-2)and field measurements(319.5 m at adjacent monitoring borehole Y1),with a relative error of 4.2%.