Abstract: In order to have the coal pore structure affected to the gas content in Liliu Mining Area, based on the mercury injection and liquid nitrogen adsorption tes t, a quantitative analysis was conducted on the full borehole diameter distribution features of the coal pore structure within the mining area. A linear ftting was conducte d on the pore structure characterized parameters with the coal adsorption constant and permeability. In combination with the theoretical analysis, the paper stated the p ore structure affected to the coal gas content. The result showed that the micro pore and transitional pore to the coal pore contribution rates would be 43% and 44% ind ividually and the medium and large pores to the contribution rate were relatively low. The micro pore to the contribution rate of the pore specific surface area was higher to 71%, then the transition pore was about 27% and the large pore was taken 0.02%. The specific surface area of the micro pore and the gas limit adsorption volume co uld meet the index function relationship. The coal specific surface area would be in a leading position of the composition and would control the coal adsorption content. The contribution rates of the medium pore and large pore would be 13% only, the influences to the coal free gas content was weak, but would have a certain positive co rrelation to the coal permeability and could be the seepage channel and storage space of the free gas.