Bio oil aqueous two phase systems were formed with ethanol and the salts of (NH4)2SO4, K2HPO4 and NaH2PO4 in bio oil on the ratio of 10:5:10(by mass). After phase separation, both the upper and the lower layers were analyzed by gas column/mass spectrometry (GC/MS). As a result, both K2HPO4/ethanol and NaH2PO4/ethanol system can enrich phenols and levoglucosan in the upperand lower layers,respectly, while NaH2PO4/ethanol system seldom changes the components of bio oil; the (NH4)2SO4/ethanol system is quit different with the other two and we have detected some components with nitrogen. Hence, NaH2PO4/ethanol is an advantage aqueous two phase system for bio oil treatment.