Abstract: In order to reveal the characteristics and differences of the key reservoir properties of coal measure gas with different coal ranks, the representative high-rank coal-bearing blocks in northern Ordos Basin, the middle-rank coal-bearing blocks in Linxing area in eastern margin Ordos Basin and low-rank coal-bearing blocks in Baiyinhua coalfield of Erlian Basin were selected as the research objects.This study was based on the microscopic fissures, scanning electron microscopy, mercury injection and liquid nitrogen adsorption and other measured data of the coal measure reservoirs.Pore types, pore structure, pore permeability of the coal measure reservoirs were analyzed.According to the abundance of dominant pore and fracture, the reservoir was divided into nanoscale pore and fracture type, micro-scale dominant type, nanoscale-micron dominant type and micron-centimeter dominant type, and the differences of the pore and fissure of different coal ranks were discussed.The results show that in the high coal rank area nanoscale dominant type is developed in coal reservoirs, nanoscale-micron dominant type is developed in the tight sandstone reservoirs, and the shale reservoirs developed micron dominant type.In the middle coal rank area, nanoscale pore dominant type is developed in coal reservoirs, nanoscale-micron pore and fracture dominant type is developed in sandstone reservoirs, and micron-centimeter fracture dominant type is mainly developed in mud shale.Also in the low coal rank area, nanoscale-micron pore dominant type is developed in coal reservoirs, and micron pore and fracture dominant type is developed in sandstone reservoirs.Low mesopores content of coal reservoir, poor connectivity of pore and throat in sandstone reservoir, and low mesopores content in mud shale reservoir are the direct reasons that hinder gas permeation and migration.From good to bad, the physical properties of coal measure reservoirs are successively low rank reservoir, middle rank reservoir, and high rank reservoir.With the coal rank getting higher, the macropores and micropores content of coal decrease, the transition pores content increase, and mesopores change slightly.The changes of sandstone and mud shale reservoirs are similar.The macropores and mesopores content decrease while micropores and transition pores content increase.The physical properties differences of coal reservoirs among different coal ranks are related to the coal metamorphic grade.Diagenesis is the main reason leading to the physical properties differences of sandstone and mud shale.