Abstract: Trypsin and flavourzyme were selected to hydrolyze Red Sea Bream bone, the hydrolysate was separated into 4 peptide parts by ultrafiltration membranes with 10, 5, 3ku respectively, the ·OH, DPPH· and O2-· scavenging ability, Fe3+reducing activity and oil antiactivity of the different parts were studied respectively. The results showed that the different parts all had antioxidant activity, and the strength of their antioxidant capacity was in the order:peptide parts below 3ku>3⁵ku peptides>5¹0ku peptides>peptides over 10ku.