Abstract: In order to investigate the effect of coalification degree on tar composition characteristics of coal sample pyrolysis, pyrolysis experiments of coal samples were carried out with a thermal analysis device. On this basis, the composition characteristics of pyrolysis tar were studied by gas chromatography-mass spectrometry (GC-MS). Research results show that the heavy component content in tar (boiling point >360 C) gradually decreased with the increase of coal rank, while the light oil (<170 ℃), phenol oil and naphthalene oil (170℃~230 ℃) and wash oil (230℃~300 ℃) in tar produced by bituminous coal S was slightly higher than that of lignite NM and bituminous coal XJ and HL. The content of aromatic compounds in pyrolysis tar containing 2 and 3 benzene ring structures is lower than that of aromatic compounds containing 1 benzene rings, and gradually increases with the carbon content in coal samples.