Abstract: According to the mining conditions of easy self-igniting and extra-thick coal seam in Kuangou Coal Mine, the air leakage between the surface and the multi-level goaf was measured by SF₆ tracer gas. The results show that: in the mining area of I010201 and I010202 working faces, when the mining areas of B₄₁, B₄₂ and B₂ coal seams do not overlap, the goaf of B₂ coal seam will not form air leakage channel with the surface; however, in the overlapped area that has been mined, it can directly form a crack communication with the surface. The air leakage velocity of the ground surface of I010201 working face to the underground reaches 62.7 m/min, and the air leakage occurs in I010403 goaf at the upper part of the closed area of I010201 working face, and the wind speed of air leakage exceeds 14.7 m/min