Abstract: In order to study CO adsorption performance of the different coal samples under low pressure, the automatic physical chemistry analyzer Autosorb-iQ-C is used to acquire CO adsorption isotherm of coal samples with different coal property under different temperature in the low pressure stage. Through the analysis of the experimental data, it is obtained that the CO gas adsorption quantity of coal increases firstly then decreases with the increase of coal metamorphism degree, which has a good correlation with the change law of porosity. The CO adsorption process of coal conforms to some assumptions of the Langmuir model under low pressure, the Langmuir model can be simplified to Henry model. That CO adsorption heat of different coal samples is between 12 to 25 kJ/mol was calculated through the Clausius-Clapeyron equation, and the CO adsorption forms of coal are mainly physical adsorption in low pressure stage, the results show that the adsorption heat is one of the main factors affecting the adsorption quantity.