In this paper, the relationship of chromatographic retention index (I) and aromatic ring number (ARN) of 49 pure reagents in Zorbax-NH2 column/hepatane chromatographic system using high performance liquid chromatography(HPLC) have been studied. The results obtained were that log I values can be divided into several regions according to ARN. They were 0.672-1.089, 1.652-2.588, 2.629-3.241, 3.447-4.160 and 4.482-5.000 for ARN 1 through 5. Those were clear-cut and could be applied to the division of aromatic ring distribution (ARD) of heavy oil products. Hence the ARD method, which was based on the results from pure synthetic compounds, has been established. On the study of quantitation, the peak-area normalization method was used to quantify the aromatics with different ARN. The method has the features of high rapidity, high resolution and long life of column. In this paper heavy oil and pitch products from seven plants have been systematically analyzed for their ARD.