Abstract: In order to investigate the evolution law of the coupling effect of particle size and temperature on gas desorption in coal, the gas desorption test was carried out under different conditions of particle size and temperature by virtue of the HCA gas desorption device in No.17 coal seam of Liupanshui Mining Area in Guizhou Province. The results show that: when the temperature is constant, the gas desorption amount and initial gas desorption amount are inversely correlated with the particle size, and the particle size inhibits the gas desorption process. When the particle size is constant, the gas desorption amount in the coal increases with the increase of temperature, and the temperature promotes the gas desorption process. Based on the improved Barrel formula and the data measured from the first 30 minutes of the desorption test, the function relation of gas desorption in coal with the coupling action of particle size and temperature is deduced. When the particle size increases from 0.1 - 0.3 mm to 0.75 - 1 mm, the coupling effect of particle size and temperature inhibits the process of gas desorption in coal, and the gas desorption capacity shows a downward trend as a whole. But it has a trend of gradual change from rapid decrease to slow decrease as the particle size increases and the law varies with temperature.