Abstract: Coal seam water injection can effectively reduce dust. With the exploitation of deep resources, the traditional hydraulic measures are difficult to achieve the ideal dust reduction effect. In this paper, FLAC numerical simulation method is used to compare and analyze the pressure evolution, plastic zone failure and pore water pressure distribution characteristics of coal rock under three different water injection modes : cyclic water injection, static pressure water injection and high pressure water injection. The dust reduction effect of various water injection modes is discussed and the mechanism of increasing permeability and dust reduction by cyclic water injection is clarified. The future research is discussed. The results show that the stress distribution of coal rock under static pressure water injection is more uniform, the plastic zone is less damaged, the wetting range is smaller, and the effect of increasing permeability and reducing dust is poor. Under high pressure water injection, stress concentration occurs in coal rock, and the plastic zone at the water injection end is seriously damaged. The wetting range is larger than that of static pressure water injection, but it is easy to cause dynamic disasters in coal rock. Compared with the previous two, the circulating water injection has the largest wetting range and the best effect of increasing infiltration and dust reduction. Cyclic water injection injects high and low pressure water into the coal body, and the water injection pressure fluctuates periodically, which causes fatigue damage to the coal body, and the particles in the pores and fissures are taken out of the coal body under the action of cyclic water pressure, which is conducive to the development of pores and fissures and increases the wetting range of the coal body.