Abstract: Taking Huolinhe Basin of Erlian Basin group and the low-rank coal reservoirs of Baiyinhua Basin as the research objects, through the analysis of the physical properties of coal reservoirs, mercury intrusion curve types, pore size distribution characteristics, pore structure types, the effect of the pore structure of low-rank coal reservoirs on coalbed methane adsorption and desorption in Erlian Basin provides a reference for the subsequent development of coalbed methane projects. The results show that the pore system of low coal rank coal reservoirs in Erlian Basin group is well developed and has large porosity. The porosity IV coal group <ⅢA coal <3-1 coal; the pore structure is dominated by small micro-pores and large pores, and the pore size of small pores smaller than 100 nm and large pores larger than 1 000 nm contribute the most to pore volume. Based on the pore size distribution ratio and the effect of pore size on coalbed methane storage and seepage, the pore structure types in the study area are divided into four categories: closed adsorption type ⅡC, open adsorption type ⅡO, closed seepage type ⅠC, open seepage type ⅠO, of which the adsorption type is most beneficial to the enrichment and production of coalbed methane. Comparing the Ⅳ coal formation, ⅢA coal reservoir in Huolinhe Basin and 3-1 coal reservoir in Baiyinhua Basin, the pore structure of ⅢA coal is the most conducive to CBM storage and development.