Abstract: The fixed bed reactor was used to study the effect of particle size and temperature on NO absorption characteristics on coal char surface and obtain adsorption equilibrium and dynamic data.The evolution of functional groups and chemical changes of coal char surface structure were studied with diffuse reflection FTIR.Functional groups,such as aromatic —NO2 and —NO were observed.The major increment was aromatic —NO2.The band intensity of —NO2 and —NO functional groups increased with decreasing particle size and increasing temperature.The results showed that particle size and temperature had a noticeable effect on the adsorption of NO gas on coal char.