Abstract: Taking Zhanjiang oyster as materials，the antioxidant activities of aqueous extracts from oysters（AEO） were researched. The results of reducing capacity determination showed that reducing capacity of 1.08 mg AEO was only equal to that of 28.8 μg VC，hence，reducing capacity of AEO was far lower than that of Vc. Through determination of scavenging three free radicals of DPPH·，·OH and ·O2 -，antioxidant activities of AEO were investigated. The results showed that scavenging rate of DPPH· with 8 mg/mL AEO was 90.63%，and the capacity of scavenging DPPH· with AEO was higher than that of VE；scavenging rate of ·OH with 0.6 mg/mL AEO was 77.23%，and the capacity of scavenging ·OH with AEO was lower than that of thiourea；·O2 - could be scavenged with high concentration of AEO. In addition，oligopeptides content accounted for 50.09% of total protein. High content of oligopeptides maybe the main cause of antioxidant activities of AEO.