Abstract: To study the influence of different particle sizes pulverized coal filling on coalbed methane permeability, the paper took II1 coal reservoir of Zhaogu No.1 Mine of Jiaozuo Coal Industry as the research object, 20 to 40 mesh, 60 to 80 mesh and 100 to 120 mesh pulverized coals were used as filled media. Under certain confined pressure, experiments were carried out on coal rock fissure permeability characteristics with different pressures and different crack widths. The results show that under certain confined pressure, with the increase of air pressure, the permeability of coal-rock fractures filled with coal powder with the same fracture width and different particle sizes increased first and then decreased, and the peak permeability decreases with the increase of coal size; in the coal-rock fractures filled with coal powder with the same mesh width, the permeability of coal rock crack increases with the filled width.