Abstract: In order to improve the pore structures and adsorption properties of coal in mining fields in Guizhou Province, and promote coalbed methane drainage and prevent coal and gas outburst, taking samples from four different coal mines in Guizhou mining areas as the research objects, we use the methods of scanning electron microscope, mercury injection and isothermal injection to carry out experimental tests. The results show that Guizhou coal develops a large number of fractures and secondary porosity, and these cracks and pores are adsorption sites and distribution channels of coal seam gas; the pore volume of Guizhou coal is between 0.146 8 mL/g and 0.228 9 mL/g, the pore specific surface area is between 15.434 m²/g and 18.260 m²/g, and the average pore diameter is between 33.4 nm to 51.4 nm, the macro-pores and fractures are the major contributors to the pore volume, the pore diameter between 5 nm and 10 nm is the major contributor to the surface area, open hole in coal is less, and the connectivity of pore is general; gas adsorption capacity and pore volume, pore surface area has a good positive correlation, and Langmuir monolayer adsorption equation can well describe the adsorption process of coal.