Gas-fat coal is one of the main coal types of coking coal. To study the structure of high sulfur gas fat coal and construct a molecular structural unit model is of great significance for desulfurization and upgrading, optimizing coking coal blending and saving high quality coking coal resources. The high sulfur gas-fat coal in Gaoyang mining area in Shanxi was selected. Its carbon, oxygen, nitrogen and sulfur structural characteristics were characterized by FTIR, ¹³C CP/MAS-NMR and XPS. The molecular structure unit model of Gaoyang high sulfur gas-fat coal was constructed by combining the results of coal quality analysis, calculate aromatic structure, fat structure and hetero atom structure parameters. The results show that the hydroxy π hydrogen bond formed by π electrons on the aromatic ring is the most important hydroxy structure of Gaoyang high sulfur gas fat coal, accounting for 73.20%. Hydroxyl self-association hydrogen bond, ether oxygen bond and hydroxyl group form a high hydrogen bond content, accounting for 24.38% of the total hydroxyl groups. The free hydroxyl content is only 2.42%, and the association structure in coal is mainly in the form of the multimer. Conjugated carbonyl and phenolic hydroxyl are mainly forms of the oxygen containing functional groups. The aryl ether and carboxyl groups are low. Methylene is the most important aliphatic hydrocarbon structure. Accounting for 41.85%. The proportion of methyl and methine groups was 29.86 and 28.29% respectively. The aromatic hydrocarbon structure mainly has three forms of benzene ring penta-substituted, benzene ring tri-substituted and benzene ring tetra-substituted, accounting for 41.42%, 30.65% and 19.82%, respectively. The aromatic hydrogen ratio and the aromatic carbon ratio is 0.34~0.35 and 0.73~0.77 respectively. The average structure size of the aromatic nucleus X_b was 0.43. The contents of thiophene, (sub)sulfone, thioether (thiol) and inorganic sulfur in coal is 35.90%, 27.61%, 18.40% and 18.09% respectively. Nitrogen is mainly present in the structure of pyridine and pyrrole, with less protonated pyridine and nitrogen oxides. The molecular structure unit has 118 aromatic carbon atoms, 5 carboxyl groups and carbonyl groups, 35 aliphatic hydrocarbon atoms, and 8, 2, 2 oxygen, sulfur and nitrogen atoms. According to the analysis of the structure of heteroatoms in coal. It is determined that the molecular structure model unit contains functional groups such as thiophene, sulfoxide, pyridine, pyrrole, phenolic hydroxyl group, ether oxygen bond and the like. The molecular structure unit model of high-yang high-sulfur gas fat coal with molecular formula C₁₆₅H₁₂₈O₈N₂S₂ was constructed.