Abstract: Aiming at the prominent problems encountered in pneumatic directional drilling construction of complex fractured soft coal seams underground coal mines, including encountering dirt bands, low drilling efficiency and frequent failure of positive displacement motor (PDM), this paper conducts research on the key drilling technologies of high-torque pneumatic PDM drills for rock boreholes. The technical bottlenecks of pneumatic directional drilling in rock boreholes were systematically analyzed. The developed pneumatic PDM drill employs a pre-contour stator structure to enhance its output torque, with relevant parameters calculated via empirical formulas, and laboratory comparative tests were carried out between the developed PDM and conventional pneumatic PDM drills in terms of output performance. The PDM rotor was optimized with a hollow rotor structure to attenuate the lateral vibration induced by the motor; meanwhile, a separately detachable disc spring vibration damping sub was developed to absorb and mitigate the vibration transmission of the drilling assembly. An orifice atomization cooling assembly is adopted to replace conventional lubricating oil, and atomized water is injected into the air supply to strengthen the heat dissipation and cooling performance of the PDM drill while realizing the lubrication effect. In addition, a filtered brush dust suppression device was developed to control the high-speed dust dispersion in the confined space at the borehole orifice. Field tests were implemented in three mining areas, and the results demonstrate that the output torque of the self-developed pneumatic PDM drill exceeds 770 N·m, representing an increase of more than 50% compared with conventional pneumatic PDM drills; the rock formation drilling rate is elevated by 2.0-3.5 times, and the PDM drill length is shortened by approximately 20%; the comprehensive per-unit drilling efficiency of coal seam boreholes is improved by about 15%, while that of rock-crossing boreholes is increased by over 80%; the footage life of coal seam boreholes is prolonged by nearly 7 times with an 80% reduction in material costs; the footage life of rock-crossing boreholes is extended by approximately 2.7 times with a 47% drop in material costs. The application of the hollow rotor structure and vibration-damping anti-drop sub effectively reduces the incidence of thread tripping and drill string dropping accidents; replacing lubricating oil with atomized water for lubrication features convenient operation, superior safety and environmental friendliness; the filtered brush dust suppression device can effectively contain high-speed dust emission at the borehole orifice.