Abstract: The gas permeability of different types of structure coal in Xin'an, Xindeng and Yanma is studied by using triaxial seepage experiment device, the conclusions are that the gas permeability of different types of structure coal increases with firmness coefficient in the same mining area; the firmness coefficient has an obvious effect on the gas permeability of classⅡcoal, the growing rate of whose gas permeability is three times of classⅠcoal and twice of class Ⅲ coal; the firmness coefficients of the different mining area have no necessary connection with the gas permeability of the different mining areas; the effect of the external stress on the gas permeability of classⅡcoal is more obvious than classⅠcoal and class Ⅲ coal.