Abstract: To investigate its effect on learning and memory,different enzymatic extractions from oyster were obtained. Oyster was hydrolyzed by five different enzymes( trypsin, flavor enzyme, neutral enzyme, alkaline protease and complex enzyme). Memory deficit mice were induced by D-gal. Five groups of mice were received 5 different enzymatic extractions by oral administration,respectively. Morris water maze was used to assess the spatial memory. The level of MDA and SOD were examined. The results showed that the escape latency in each group was reduced significantly in the last 3 days. And the escape latency in trypsin group and alkaline protease group was reduced significantly(p<0.05) in the first day and the second day,respectively. In probe trial,both time spent in target quadrant and numbers of crossing platform were significantly increased(Time spent in target quadrant:trypsin:p<0.05,neutral enzyme:p<0.05,other groups were p<0.01. Numbers of crossing platform:trypsin:p <0.05,neutral enzyme:p <0.05,complex enzyme:p <0.05,other groups were p <0.01). The level of MDA in trypsin group(p <0.05),flavor enzyme group(p <0.05) and complex enzyme(p <0.01) group was reduced significantly,respectively;while the level of SOD in all groups,except flavor enzyme group,was increased significantly,respectively(trypsin:p<0.05 neutral enzyme:p<0.01 alkaline protease:p<0.05 complex enzyme:p <0.01). This work indicated that oyster enzymatic extractions ameliorate the memory dysfunction induced by D-gal,which suggested that oyster enzymatic extractions might be developed as a new dietary supplement for treatment of age-related diseases.