Abstract: In recent years, with the continuous development of the research of high gradient magnetic separator, the dust removal of magnetized water has been continuously paid attention to. In order to study the dust reduction effect of active agent coal seam water injection, on the basis of carrying out the research on the magnetization characteristics of liquid water and the mechanism of capturing dust, the on-site active agent water injection dust reduction test was mined in the working face of Yecheng coal mine 5305. The research results show that: after the reaction of water by active agent, the magnetic field provides energy to water molecules, the surface tension of water is reduced, the solubility and penetration ability is enhanced, and the viscosity is reduced, so as to enhance the wetting performance of water on dust, and enhance the capturing ability of respiratory dust; after 5305 comprehensive mining face is injected with water by active agent to reduce the dust, the full-pressure dust concentration is reduced by an average of 70.5%, and at the return wind of the face, the dust concentration is reduced by 10.2%.