Light oil, phenol oil, naphthalene oil, washing oil, and anthracene oil separated from a high-temperature coal tar (HTCT) were extracted via a modified HCl/NaOH extraction method to obtain acid-soluble portions (ASPs), base-soluble portions (BSPs), and acid/base-insoluble portions (ISPs), which were further analyzed with a gas chromatograph/mass spectrometer (GC/MS) to understand the composition of the HTCT. The results show that the recoveries of the 3 portions separated from each fraction decrease in the order of ISPs >> BSPs > ASPs. According to the analysis with a GC/MS, a total of 403 compounds were detected from the 5 fractions and their separated portions. Noteworthily, nitrogen-containing organic compounds, oxygen-containing organic compounds, and arenes dominate BSPs, ASPs, and ISPs, respectively. Combined with the distribution of fragmental ions in the mass spectra, detailed pathways for fragmentating the major compounds in different fragmentation modes were proposed, which facilitates the identification of different compounds. Moreover, possible compound separation pathways were investigated.