Abstract: In order to realize the efficient water injection to coal seam with large mining depth，low porosity in Tengdong Shengjian Coal mine，and reduce the dust concentration in coal mining face，the internal law of the coal seam water injection and seepage process was qualitatively analyzed based on a unified unsaturated-saturated flow continuity equation and stress equilibrium differential equations; Secondly，with the mine actual geological conditions and the mine coal seam seepage equation above，the seepage pressure distribution of borehole at 50 m and 80 m was simulated by using COMSOL Multiphysics software.Then，combined with the conclusion from numerical simulation，80 m of borehole and the related mixed hydrostatic water injection technical parameters were chosen，and applied into 3 lower 105 working face.Finally，after the implementation of water injection，and through the field monitoring，average dustfall rate of total dust at working face was 65.96%，and average dustfall rate of respirable dust was 60.6%.It effectively reduced dust concentration at working face.The research provides references for implementing the coal seam water injection in similar coal mines.

Key words: Deep mining, Low porosity, Numerical simulation, Hybrid water injection