Abstract: On the basis of compositions,molecular weight distribution and amino acid composition of black-bone silky fowl(BSF) oligopeptides,the antioxidant activities in vitro of BSF oligopeptides were generally evaluated from four respects by determination of the scavenging activities against DPPH radical,hydroxyl radical and superoxide radical as well as reducing power.Results indicated that the major molecular weight of BSF oligopeptides was less than 1 000 u(96.74%),and small peptides with the molecular weight range from 140 to 500 u were dominated(78.53%).BSF oligopeptides had strong antioxidant ability in vitro and the antioxidation correlated positively with mass concentration.The median inhibitory concentrations(IC50 values) of DPPH radical,hydroxyl radical and superoxide radical scavenging activities were 4.5,4.5 and 12 mg/mL,respectively.Meanwhile,the reducing power of BSF oligopeptides at 9.19mg/mL correlated with that of ascorbic acid at 0.02mg/mL.