A new separation process should be applied to improve the quality of pitch that will be used for the production of high-performance carbon materials, In this study, aromatic heavy oil has been fractionated with supercritical n-hexane. Dynamic supercritical fluid extraction was applied, and the dependence on the temperature and pressure of the extraction behavior and selectivity has been investigated. Aromatic heavy oil was fractionated into several fractions, which have a boiling point distribution that is clearly different from that of the feedstock, by extraction under vapor-liquid-like phase behavior conditions. The boiling point distribution of the extracts sampled under liquid-liquid-like phase behavior conditions, however, was almost the same as that of the aromatic heavy oil. As the extraction temperature increased, the extraction rate also increased without a compensation for the extraction selectivity of the boiling point distribution. The increasing of extraction pressure, however, decreased the extraction selectivity of the boiling point distribution although extraction rate was increased. Asphaltene was rejected by extraction under vapor-liquid-like phase behavior conditions, but there was no chemical composition extraction selectivity under liquid-liquid-like phase behavior conditions.