In this study, the aromatic nuclear structures of bituminous coal were classified and quantified. Samples of coal (C%, on a dry, ash-free basis, in the range of 77.4-81.7%) were subjected to sequential oxidation with basic permanganate. The filtrates and residues were quantified using high-performance liquid chromatography, gel permeation chromatography, and ultimate analyses. The aromatic structures of the coals are generally categorized into three types based on oxidation characteristics: (1) Type I consists of aromatic nuclei oxidized into benzene poly(carboxylic acid)s, (2) Type II consists of aromatic nuclei excessively oxidized into small-molecule fatty acids (SMFAs), and (3) Type III consists of unoxidized aromatic nuclei. The concentrations of Type I in coals 1-3 (Coals 1-3 represent the rank range of samples of coal, as shown in Table 1) are 2.01, 2.20, and 2.93 mmol/g, respectively. Type I consists of aromatic hydrocarbons and their derivatives based on oxidation of representative model compounds (methylbenzene, naphthalene, tetrahydronaphthalene, anthracene, and pyrene) and nuclear magnetic resonance analyses of raw coals. Moreover, the concentrations of nitrogen-containing aromatic nuclei of Type II in coals 1-3 are 0.37, 0.62, and 0.51 mmol/g, respectively. Type II is composed of aromatic heterocycles (benzofuran, carbazole, indole, benzothiophene, and so on), phenol, and anisole. The content of Type III is extremely low, and the concentrations of tetrahydrofuran (THF) extracts of Type III in coals 1-3 are 0.096, 0.004, and 0.057 mmol/g, respectively. THF extracts of Type III consist of diphenyl, diphenyl ether, and diphenylene oxide. THF-insoluble substances of Type III consist of polycyclic aromatic hydrocarbons, such as truxene, decacyclene, and their derivatives. The polycondensation of polycyclic aromatic hydrocarbons gradually increases with increasing coalification of bituminous coal. The polycondensation of nitrogen-/ sulfur-containing aromatic nuclei rapidly increases when carbon content in bituminous coal reaches 81.7%. The average size of the aromatic nuclear structures in the coal (C%, daf, 77.4-81.7%) contains 2-ring to 3-ring with a maximum of 5-ring in the higher-ranked coal (C%, daf, 81.7-85.0%). The results provide further knowledge of the structural units and molecular reaction characteristics of the aromatic nuclei of bituminous coals with different coalifications.