Abstract: X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy were used to study the surface features and main functional groups of huminite and inertinite from Mengdong post-Jurassic lignite.The results indicate that the particle surface of huminite is uniform and there are many discrete powders around it, which mainly contains clay minerals.The surface of inertinite is rough and some of them have plant fibrous structure.Clay and silicate minerals are mainly minerals.Four forms of carbon are roughly the same in huminite and inertinite group.Huminite is lower content of C—C/C—H than inertinite, but the content of phenolic or ether carton(C—O) is higher than inertinite, which shows aromaticity of huminite from Mengdong post-Jurassic lignite is higher than inertinite.The content of carboxyl(O=C—O) and carbonyl(C=O) of inertinite is higher than huminite.The occurrence state of oxygen in the two macerals are mainly in the form of phenolic hydroxyl oxygen and ether oxygen bond oxygen, and the contents of inorganic oxygen and adsorbed oxygen are both less.The content of sulfur in inertinite is very little which can be negligible.The aliphatic sulfur is the main form of sulfur inhuminite, and the content of thiophene sulfur is very little.The results are helpful to fully understand the structural and property differences of the macerals of the mengdong post-Jurassic lignite and provide a basis for flotation separation of the macerals of coal.