Abstract: Using the micropore structure analyzer of 9310 type,the pore characteristics in coals and roof and floor rocks of seams are studied systematically.It is concluded that pore development in coal is controlled comprehensively by the factors such as metamorphism degree of coal,coal component,coal forming plant and posttectonic rupture;the pore development in detrital rocks is controlled mainly by the grain size of rock and filling and cementing degrees;and the pore development in limestone is controlled mainly by the corrosion intensity.