Abstract：The model of gas effusion and air exchange in inhomogeneous goaf was established based on two-phase miscible gas seepage-diffusion equation. The model is solved by means of upwind Galerkin numerical method，and the basic fluid mechanics principle of the gas transport and distribution is described by means of visualization way. On the basis of mechanical disposal，the gas effusion in the goaf with gas-tight roof and floor is treated as two-phase gas miscible flow；but the calculation of the flow pattern (velocity field) is solved by regarding it as a seepage problem of incompressible gas. So it can avoid the error and distortion from incompressible gas seepage-diffusion model in calculating gas distribution because of super saturation solution in the result. The gas source in goaf is described by negative exponential attenuation function. An example provided in the case of wind is increased，which shows the dynamical balance feature between the air pressure in working face and gas pressure in the goaf. Compared with the result calculated as single-phase flow，the gas distribution results between them are almost the same when the speed of air is relatively high，if not，there is a large difference between the results. The critical air speed when the difference appears in the example is 0.091m/min，but the gas distribution is significantly different in the deep part of the goaf.
