Biological liquefaction of nitric-acid-oxidized low-rank coal is well-documented in the literature. However, few studies focused on the macromolecular structure of nitric-acid-oxidized low-rank coal. In this paper, Fushun nitric-acid-oxidized coal was first analyzed by Fourier transform infrared spectroscopy (FTIR) and C-13 nuclear magnetic resonance (NMR) spectra to investigate its elemental composition and organic functional groups. Then, the coal macromolecular structural parameters were calculated, and its structural unit was constructed. The results showed that the Fushun nitric-acid-oxidized coal structural unit had a molecular formula of C192H161N9O39. Carbon existed in the form of carboxyl and alkyl with 1-3 carbon atoms, besides aryl. Oxygen existed in the form of carboxyl, carbonyl, and phenolic groups, ether bond, etc. Nitrogen existed in the form of nitryl, amide, etc. The hydrogen aromaticity, length of the side chain, ratio of aromatic carbon, and ratio of phenolic carbon were 0.086, 0.567, 0.543, and 0.114, respectively.