Abstract: In order to study the gas flow pattern in the coal seam fractures and the changes of gas permeability, we use the experiment system which includes coal with gas, heat flux, solid, to carry out the gas seepage experiment for coal samples with persistent cracks. By changing the gas pressure difference on both ends of the coal samples, we can get the relationship between gas seepage speed and gas pressure difference on both ends of the coal samples, and solve the permeability under different gas pressure sequentially, then fit the experimental data, analyze the reasons of the permeability change. The results prove that in coal samples with persistent cracks, the gas seepage speed increases with the increase of gas pressure difference on both ends of the coal samples, and the procedure shows a parabola relation. Under the condition of higher loading stress, the gas flow in the coal seam fractures exists the slippage effect; with the increase of gas pressure difference, the contribution rate of slippage permeability to gas permeability also increases.