Abstract: To achieve efficient pressure relief and permeability enhancement in hard-thick coal seams, a field trial and effectiveness evaluation were conducted using the sectional hydraulic fracturing technology via underground directional drilling in coal mines. Based on mine-specific conditions, the fracturing equipment and key parameters were determined, and the variations in injection pressure and fluid volume during the fracturing process were analyzed. Surface and underground microseismic monitoring technologies were employed to evaluate microseismic events and fracture distribution during staged fracturing. The results demonstrated that: The maximum injection pressure reached 34 MPa in 1# fracturing borehole and 26 MPa in 2# fracturing borehol, meeting the design targets. The trend of injection pressure (initial increase followed by decrease) characterized the initiation and propagation of fractures in the coal mass. Each fracturing stage induced multiple fractures within the target coal seam, with fracture distribution exhibiting near-axisymmetric patterns on both sides of the boreholes. The maximum fracture propagation range on a single side reached 32 m, confirming effective fracturing in the hard-thick coal seam. This study provides technical references for pressure relief and permeability enhancement in similar coal seams.