Abstract: In order to reduce the coal dust concentration and gas emission in fully mechanized mining face of Jiulishan Coal Mine, based on the coal seam characteristics of Jiulishan Coal Mine and the actual situation of 16051 working face, on the basis of making full use of gas extraction borehole, the long hole and low pressure seepage water injection technology in return air lane was explored.Combined with the short-hole and medium-pressure water injection technology in working face, the comprehensive water injection mode of medium and low pressure was established and carried out.The coal seam water content, coal dust mass concentration and gas concentration of different region were investigated by regional comparison test.The field application results show that: the comprehensive water injection effect of medium and low pressure is good, the coal seam water content is increased by 2.94 times, and the mass concentration of coal dust is reduced by more than 80%.The gas in the working face is released evenly, and the gas concentration in the return air lane is reduced by more than 30%, which achieves a better water flood effect.