Abstract: Objective: To investigate the effect of soft-shelled turtle peptide (STP) on the lifespan and antioxidant activities of Drosophila melanogaster. Methods: The soft-shelled turtle peptide was prepared by enzymatic digestion. The molecular mass distribution and amino acid composition of STP were measured.Male and female Drosophila melanogaster were fed on a diet supplemented with different doses of soft-shelled turtle peptide (0.2%, 0.4%, 0.8%). The antioxidant effect of soft-shelled turtle peptide was evaluated by analyzing the survival rate and measuring the activity of superoxide dismutase (SOD), catalase (CAT) and the content of malondialdehyde (MDA) of D. melanogaster. Results: The results showed that STP were mainly constituted with peptides which had relative molecular weight between 180 and 500 Da. Moreover, STP were rich in proline, lysine and leucine. After treating with STP, compared with the control group, mean life span in high-dose group were significantly increased by 10.80% (P<0.05) and 14.01% (P<0.01) for female and male flies. Maximum mean life-span in high-dose group were significantly increased by 6.35% (P<0.01) and 13.22% (P<0.01) for female and male flies. The activity of SOD in high-dose group were significantly increased by 28.40% (P<0.01) and 15.08% (P<0.01) for female and male flies. The activity of CAT was increased by 33.50% (P<0.05) and 38.05% (P<0.01) while the content of MDA was decreased by 33.33% (P<0.01) and 34.62% (P<0.01), respectively. Conclusion: Soft-shelled turtle peptide can increase a series of antioxidant enzyme activities and decrease lipid peroxidation to prolong life span of D. melanogaster. Thus, STP may have potential anti-aging effect.