Abstract: Under the influence of igneous rock invasion and burial depth, the adsorption capacity of CO of coal under high temperature and high pressure varies greatly, and CO attached to the surface of coal body under the condition of far more than the critical temperature and pressure is in supercritical state, resulting in the occurrence of abnormal CO surge in coal seams under such environmental conditions. Then it affects the accuracy of prediction of spontaneous combustion of coal seam by the change of CO concentration. In order to study the change of supercritical CO adsorption capacity of coal body when the environmental pressure exceeds the critical pressure of CO, and to predict the supercritical CO adsorption capacity of coal seam under different temperature and pressure, based on Polanyi adsorption potential theory, from the perspective of potential energy change, through combining isothermal adsorption experimental data, the relationship model between the pressure, temperature and CO adsorption capacity can be used to predict the adsorption capacity of CO gas on coal body at different temperatures and pressures, which provides an effective theoretical basis for improving the index gas prediction method of predicting spontaneous combustion of coal seam by CO concentration.