Abstract: The nanoscale pores of coal are the main adsorption place for CH4. According to the liquid nitrogen adsorption experiment of 12 coal samples in the southern of Qinshui basin, the volume, specific surface area, distribution and the shapes of the nanoscale pores(1.5~100 nm) are determined. Furthermore, the variations of pore characteristics with rank, maceral composition and mineral have been investigated. The results showed that the BJH volume and BET surface area values are separately from 0.000 5 to 0.003 45 cm³/g and 0.196 to 2.654 m²/g. The pore volume and the surface area are respectively controlled by transitional pores（10 to 100 nm）and sub-micropores（1.5 to 5 nm）. According to the liquid nitrogen adsorption loops which can be divided four types, the pore shapes can be divided into open, semi-enclosed and fine bottleneck empty shapes. The volume and surface area decreases with the increasing of maturity, then increases with further increase of coal rank. A weak correlation does exist between specific surface area and vitrinite content and mineral content.