Abstract: Electron paramagnetic resonance(EPR)technique was used to investigate the antioxidant activities of three carotenoids(lycopene,lutein,and β-carotene)by comparing their scavenging abilities against 1,1-diphenyl-2-picrylhydrazyl(DPPH·)and hydroxyl radical(·OH). The results showed that both DPPH and Fe²⁺(fixed Fe²⁺:H₂O₂=1:10)concentrations had a good linear relationship with the EPR signal,and the correlation coefficients R² were greater than 0.99. The three kinds of carotenoids had certain scavenging effects on DPPH· and ·OH,and the scavenging ability increased with the increasing of concentration and time. Lycopene had the strongest antioxidant activity among the three carotenoids,and β-carotene had the weakest antioxidant activity. The scavenging values for DPPH· by lycopene,lutein and β-carotene with concentration of 0.6 mmol/L were 95.4%,76.7% and 47.7%,and for ·OH were 56.6%,29.1% and 14.0%,respectively. Compared with UV-visible spectrophotometry(UV-Vis),this method can avoid the color interference of carotenoid itself. These results provide information for improving the evaluation method of antioxidant capacity of such natural food additives.