Abstract: In order to study the influence of gas seepage on the stability of coal layers, some simulating tests of uncovering coal seam were made with different devices arranged in the laneway including air-tight door, metal fences, anti-fitter layers and no obstructive laneway. Coal sample is compacted by 15 MPa and its particle size distribution is less than 4.75 mm. The inner diameter of sample cell is 199 mm and its length is 1 000 mm. CH₄ is replaced by N₂ during the tests, the injecting gas pressure is 0.40 MPa. Ball valve is made as uncovering coal apparatus and its inner diameter is 40 mm. No axial pressure is loaded on coal sample during tests. Test results show that the outburst intensity decreases with the decreasing of permeability of the laneway. The outburst caves are developed from the outside to the inside and extend from the cave center to the surrounding. At the end of the outburst, the thickness of the falure sublayer increases with the decreasing of the gas pressure gradient. A suggestion is made to uncover coal seam by air-tight door, metal fences and anti-fitter layers.