Abstract: Nitrogen compounds were extracted from coker gas oil and straight run diesel oil by chromatography with neutral silica adsorption column. Then the nitrogen compounds were concentrated and separated into basic and non-basic types using acid-modified silica column. The identification of nitrogen compounds in the extracts was performed by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-nitrogen chemiluminescence detection (GC-NCD), as well as verification of peak assignments with those reported by others. Results showed that in straight-run diesel, neutral nitrogen compounds, mainly benzocarbazole nitrogen compounds, occupied more than 70% (mass fraction) of the total nitrogen compounds; in coker gas oil, nitrogen compounds including pyridine, aniline, indole, quinoline, and carbazole were found, and the mass fraction of total neutral nitrogen compounds was slightly over that of basic nitrogen compounds occupied more than 50% of the total nitrogen compounds.