Abstract: Multiple kinds of pores exist in the coal ranging from nm～mm sizes, and a systematic characterization of the coal pore structure is of significant importance on clarifying coal physical parameters and coalbed methane production. Based on the system sampling in different areas of the east margin of Ordos basin, the pore system of coal at different scales was characterized by low temperature carbon dioxide and liquid nitrogen adsorption, high pressure mercury intrusion and low field nuclear magnetic resonance (NMR). The results show that the CO₂ adsorption can be used for characterization of pores between 0.6～1 nm, and the liquid nitrogen adsorption suits for pores between 1～20 nm, and the mercury intrusion can generally characterize pores lager than 18 nm. Based on mercury intrusion saturation, mercury withdraw efficiency and porosity values, the coals can be divided into 7 types, with a discussion to their mercury intrusion and withdraw curves. The NMR method was used for characterization of pore sizes variations and connectivity of different vitrinite reflectance and different burial depth coals, which shows that the micropores increases as with the increase of vitrinite reflectance and also burial depth. The relative results can be used for characterization for coal physical parameters and a systematically characterization of coal pore size distributions of multiple scales.