Supercritical extraction of light hydrocarbon from residues remaining after distillation of crude oil, has been carried out by n-pentane solvent. In order to investigate the extraction characteristics upon the variation of temperature and pressure, the experiments were performed at 483K, 503K and 523K with pressure range from 4.4MPa to 12.0MPa, respectively. The extraction yield has shown to be increased with the system pressure and the temperature approaching down to critical state of n-pentane from the supercritical region. A drastic fall down exhibited in yield under critical density may be stemmed from a phase transition from liquid-liquid-like system to a liquid-vapor-like system. GC analysis of extracted oil revealed that the earlier extracts contain relatively lighter compounds, and the carbon number distribution of the extract has shifted toward the heavier carbon number with lapse of operation time.