Abstract: The experiment was conducted to determine the effects of chitosan on growth performance and antioxidant capacity of Drosophila melanogaster. The research was focus on the effect of supplied with different doses(0%,0.01%,0.05%,0.10%) of chitosan on Drosophila melanogaster life span,antioxidant enzymes activities and their encoding genes expressions. The results showed that LD50 of Drosophila melanogaster had no difference between treatment groups,compared with control group(p>0.05). Supplying with 0.05%,0.10%chitosan could increase average life-span and maximum life-span of Drosophila melanogaster significantly(p<0.05). Chitosan could increase GSH-Px activity significantly(p<0.05). Supplying with 0.05%,0.10% chitosan could increase SOD activity significantly(p<0.05) of Drosophila melanogaster,while the content of MDA was decreased(p<0.05). Real Time-PCR assay results showed that the m RNA expression of Cu Zn-SOD,Mn-SOD,CAT and PHGSH-Px(p<0.05) were increased. In summary,the results showed that chitosan had a promotional function on lengthening growth and development,improving the activity of anti oxidative enzymes and gene expression level significantly,enhancing the antioxidant capacity and postponing senility of Drosophila melanogaste.