Abstract: The study of the CO adsorptive capability of every maceral of low rank coal is highly significant for choosing the index gas for estimating spontaneous combustion of low rank coal.Under different temperature and pressure,the isothermal adsorption tests of pure inertinite and vitrinite are carried out at 30 ℃,40 ℃,50 ℃,55 ℃,60 ℃,65 ℃ respectively,after analyzing the proximate,element and maceral of coal samples.The results show that the adsorption isotherm of CO can be described by Langmuir equation at low temperature(T≤50 ℃);and the relationship is linear between the coal adsorption quantity of CO and the pressure at high temperature(T>50 ℃),it can be described by Henry equation,which increases with pressure,however,the temperature’s effect is so complex that the mechanism need to study further.At the same time,the fusinit,oxygen-function groups and negative func-tional groups are high popularly in low rank coal samples,especially,the content of hydroxide(—OH) has great influence on CO adsorption in that the inertinite has stronger effect than vitrinite on adsorptive capability of low rank coal samples.