Abstract: The accurate prediction of the height of the water-conducting fracture zone is a critical issue in coal mine water hazard prevention and safe production, with its precision directly impacting water resource protection and mining safety in mining areas. Guided by the "full-columnar" academic concept, this study comprehensively employed laboratory tests, theoretical analysis, similar physical simulations, and numerical modeling to conduct a thorough determination of the rock physico-mechanical parameters across the entire strata of the overlying rock structure and mining conditions of the 2–2 coal seam in Xinjie No. 1 Mine. On this basis, taking Borehole 18–5 as an example, the key stratum position within the overlying rock and the height of the water-conducting fracture zone in this area were accurately determined. This revealed significant deviations caused by the conventional homogenization approach, which uses physico-mechanical parameters from rock samples at a single depth to represent the parameters of similar rock types, in identifying the key stratum position and the height of the water-conducting fracture zone. Based on the full-columnar coring and parameter results from 20 boreholes, the global distribution characteristics of the height of the water-conducting fracture zone in the overlying rock of Xinjie No. 1 Mine were delineated. In areas where the water-conducted fracture zone is close to the Cretaceous aquifer, this study investigated the correlation between mining thickness and the development characteristics (both height and aperture) of the fracture zone under limited-thickness mining. The results indicate that: Calculations using the full-columnar rock mechanical parameters of the mine enable precise determination of the key stratum position and the height of the water-conducting fracture zone. Compared to the homogenization method, which yielded a water-conducting fracture zone height of 276.84 m and a fracture-to-mining ratio of 30.76, the full-columnar analysis of Borehole 18–5 showed a height of 172.02 m and a ratio of 19.11. The latter aligns with field measurements from the adjacent Hongqinghe Coal Mine in the same mine field. Based on the borehole coordinates and calculated water-conducted fracture heights from Xinjie No.1, a global distribution map of the fracture zone development heights was plotted. The fracture-to-mining height ratio across several working faces ranges from approximately 19.2 to 25.4. In some later-stage working faces, the fracture zone is close to the Cretaceous aquifer, marking them as key areas for water hazard prevention, coal mining, and groundwater resource protection. The correspondence between different mining thicknesses and the development height of the water-conducting fracture zone was revealed. For specific areas of the Xinjie No.1 mine, it was found that a mining thickness of 7–9 m would cause the water-conducted fracture zone to extend into the Cretaceous aquifer. Analysis indicates that if backfilling is not employed, reducing the mining thickness to 5 m is necessary to ensure the stability of the aquifer. The research findings provide guidance for formulating the coal resource development plan for the No. 1 Mine Field, assessing the feasibility of limited-thickness mining, or exploring combined modes of limited-thickness mining and backfill mining, along with their coordinated protection with groundwater resources.