Abstract: The gas adsorption and desorption test system in high and low temperature was used to test the gas adsorption isotherm of coal at supercritical temperature. Based on the DRK adsorption theory, gas adsorption parameters were obtained by using the method of segmentation fitting from low to high pressure, and the pore size variation of gas adsorption was calculated and analyzed in the same time. The research shows that the adsorption capacity of coal to gas is enhanced with the decreasing of temperature. At the low pressure conditions, gas molecules are preferentially adsorbed in pores with the smaller pore size. Gas molecules are preferentially adsorbed in pores with the larger pore size at high pressure conditions. At the same adsorption temperature, the coverage area of the adsorbing gas in the coal pores increases from low to high pressure and the average pore size of the adsorbing gas also gradually increases. Both the adsorption coverage area and the average pore size increase with the decreasing of temperature, which is that the uniformity of the coal surface energy increases and the adsorption capacity enhances with the temperature decreasing.