Abstract: According to the complex loaded status of the coal in front of working face and heading face, the paper used a self-developed loaded coal or rock gas se epage experimental system, studyed the variation characteristics of permeability of coal with different moisture contents in the processes of repeated loading-unloading confining pressure. The results showed that both dimensionless permeability and damage coefficient of permeability decreased with the increase of confining pressure, and the decreasing amplitude tending to be gentle gradually. Stress sensitivity in the first process of loading was more obvious than the second process. As moisture Co ntent increased, stress sensitive coefficient increased. The variation of permeability was incomplete reversible in the process of loading-unloading confining pressure. T he damage of permeability was very big in the first process of loading-unloading. It also increased with the increase of moisture content the damage of permeability was small in the second process of loading-unloading. The research results could not only provide experimental basis for further understanding coal seam gas migration la W, but also provide theoretical support for gas drainage and prevention and control of gas disasters in coal mines.