By use of mercury intrusion, low nitrogen adsorption and scanning electron microscopy, the pore structure and seepage ability of three samples from the major coal seam in the Zhu-Zang syncline of the Zhina coalfield were analyzed. Data show that pore in the samples is dominated by transitional pore, macro- and micro-pores account for a large proportions, with minor mesopore. Pore specific surface area come mainly from the transitional pore and micropore. Pore with large diameter is open and pore with small diameter is semi-open. Difference of the pores and fractures among three samples may be the reason from which the air permeability of the Qinshan sample is higher than that of the Hongyanjiao sample.