By using self-made “Coal Containing Gas Thermal-Hydrological-Mechanical (THM) Coupling Experimental Equipment”, an experimental study is carried out to investigate the gas seepage law of containing-gas coal during the complete stress-strain process with different original water contents. Under the conditions of constant gas pressure and confining pressure, and the experimental results are compared with the field test of the gas emission variation of coal seams before and after being infused. The research results show that the triaxial compressive strength and the elastic ratio of coal decrease with the increase of original water content in coal, but the axial strain of coal increases and the absolute value of transverse strain and volume strain of coal increases at the triaxial compressive strength; the methane effective permeability of coal decreases throughout the complete stress-strain process. Outburst prevention by coal seam infusion attributed is analyzed from two aspects: the mechanics of coal and the gas flow in the coal seams. The higher original water content in coal seams is, the smaller the risk of coal and gas outburst becomes. So the original water content in coal seam can be treated as a significant criterion for the judgments of coal and gas outburst criticality.