Abstract: In order to reduce the coal dust concentrations at fully mechanized mining faces and the harm of dust to miners and equipment, coal seam water injection experiments were carried out at the test mining face of No.3 coal seam in Xishan coal field. Dust concentrations and dispersion were measured at the measuring points of the mining face to analyze the coal seam water injection effect and its effects on the dust concentration and the particle size distribution. The results show that when the amount of water injected into the test seam through a single hole is 440 m³,the internal water content increases by average 1.02%, the external water content increases by average 2.21%, the distribution interval of coal dust particle sizes becomes shorter, the average particle size decreases, the total dust concentration at the whole mining face decreases by average 28%, the respiratory dust decreases by average 32%.

Key words: coal seam water injection, coal dust concentration, median particle size, coal dust particle size, dust reducing effect