Abstract: In this paper,three extracts named ME45,ME60 and ME80 were precipitated by 45%,60% and 80% EtOH from Perna viridis respectively.Their antioxidant activities were compared by scavenging activities for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals,superoxidized radicals (· O2-),hydroxyl radicals (· OH),total antioxidant activities (TAC),and inhibitory effect on lipid peroxidation (LPO) in vitro.The results showed that all precipitations had antioxidant activities and were dose-dependent.Different antioxidant activities were shown among different reaction systmes of three fractions.In TAC,· O2-,and LPO reaction systems,the antioxidant activities order was:ME80 > ME60 > ME45.ME60 fraction had better scavenging effects than ME80 and ME45 for DPPH ·.In the scavenging · OH system,the order of removing ability was:ME45 > ME80 > ME60.In conclusion,ME80 fraction showed relatively strong antioxidant activities,a good potential as a natural antioxidant,and worth of further exploration and application.