Supercritical carbon dioxide was used to extract styrene monomer and ologomer from bulk polymerized polystyrene solution. Extraction was performed with different pressure(13.7, 20.5, 27.3 MPa) and temperature(303.15, 313.15, 323.15 K). A continuous extraction apparatus was used for this study. After 200.0L carbon dioxide per 90g polystyrene solution was consumed for extraction, the monomer and oligomer contents in the bulk polymerized solution were decreased by 6-25 wt%. As the pressure increased at fixed temperature, the amount of extracted oligomer and styrene monomer were increased and average molecular weight of polystyrene in residue and extract was increased. As the temperature increased at fixed pressure, the amount of extracted monomer was increase, however, oligomer content and average molecular weight of polystyrene in residue and extract were decreased. Due to low solubility of polystyrene in supercritical carbon dioxide, polydispersity index of residue was decreased by 5% after extraction.