Basing on finite element method and visual display technology,this paper analyses the gas drainage problem of goaf in Dalong mine.It is simulated theoretically that the gas collection course in the falling porous media of heterogeneous at the upper corner of goaf,showing immediately the mechanics of porous flow principle of the flow pattern in goaf and gas distribution movement when gas is being drained.The goaf flow pattern is calculated based on air leakage seepage equation of heterogeneous porous media,and gas transfer diffuse equations are recounted based on the binary mixture equation of gas-air,and it is fully considered that the heterogeneous feather of boundary caving has a certain influence in the calculation.Using finite element method,the justified drainage-flux and ventilation-flux of working face are concluded.