More than 60 heavy oils samples, belonging to the hydrogen adding tail oil, catalytic oil slurry, catalytic heavy oil slurry and catalytic heavy tar waxy oil, which taken from different processing units in Nanjing Refinery, are analysed by H-1 NMR and column chromatography. The analytical data of the heavy oils by two methods are compared and correlated, while good relationships between the specific area proton's percentage in H-1 NMR spectra and the contents of paraffinic and alicyclic hydrocarbons ((P + N)%), aromatic hydrocarbons (A%) are found. Our H-1 NMR method in calculating the amount of (P + N) and A in heavy oils proved fast, convenient and reliable. (C) 2002 Elsevier Science Ltd. All rights reserved.