It is difficult to determine the magnitude and distribution of permeability in gob areas, which are therefore treated as homogenous and isotropic generally. Another way to computer the distribution of permeability is based on the presupposed distribution of expanding coefficient of falling rocks. In view of the complex geological conditions of gob areas, the two methods are both subjective and arbitrary in a large degree. By importing the conception of boundary layer, the hypothesis of free deposited permeability of gob areas is put forward here. By setting the reasonable limit magnitude of permeability, namely the free deposited permeability as maximum whereas the sufficient compressed permeability as minimum, a more exact method is deduced to analyze and determine the distribution of permeability in gob areas. The application of this hypothesis in the numerical simulation of seeping flow filed in a gob area indicated that the distribution of permeability based on the hypothesis is more compliant to the fact.