In this article, a middle distillate oil obtained from a coal hydroliquefaction pilot plant was characterized by modern analytical instruments. First, using 1H and 13C nuclear magnetic resonance, the distribution of hydrogen and carbon atoms were obtained, and the presence of configurations such as long aliphatic carbon chains, alkyl-substituted aromatic ring, and partially hydrogenated aromatics in the middle distillate oil was found. Then the oil was separated into three fractions: saturates, aromatics, and polars by neutral silica gel liquid chromatography, and the detailed compositions of saturates and aromatics were respectively analyzed by gas chromatography-mass spectrometry. The results show that the aromatics fraction is the most abundant one in this oil, but they are not normal aromatics and mainly consist of dicyclic-, tricyclic-, and tetracyclic-partially hydrogenated aromatics with carbon atom numbers from C10-C21, such as tetralin, alkyl-substituted tetralin, hydrophenanthrene, hydroanthracene, hydropyrene, and so on. Saturates mainly comprise n-C12-C27 alkanes. These results are of significance for the further processing and marketing of this oil.