Abstract: DPPH, BCB and TBARS methods were separately used to determine antioxidant activities of oregano oil, carvacrol, citral and cinnamaldehyde .Results indicated that BHT, oregano oil, carvacrol, citral and cinnamaldehyde have quick DPPH free radical scavenging reaction speeds.And scavenging ability significantly enhanced with its concentration increased, and gradually stabilized.The IC50 were 1.2, 4.3, 3.7, 7.2, 3.1g/L.When antioxidant activity was determined by BCB method, BHT, oregano oil, carvacrol and cinnamaldehyde exhibit excellent oxidation resistance, and the antioxidant performance enhanced with the increase of concentration.The IC50 were 0.1, 2.2, 3.4, 1.9g/L.When antioxidant activity was determined by TBARS method, BHT, oregano oil, carvacrol, citral and cinnamaldehyde showed better antioxidant properties, and the antioxidant index increased along with the concentration increased.This study showed that oregano oil, carvacrol and cinnamaldehyde could be used as natural antioxidants in food processing.