Abstract In this experiment we selected the Fe3+ reduction system and representative free radical systems as these indexes, which were used to evaluate the effect free radicals scavenging and antioxidant activity of Lophius litulon skin collagen peptides in vitro. Then the collagen peptide compositions were separated by ultrafiltration membrane and collected scavenging hydroxyl free radica activity of the best component in vitro. After that, aging model mice was constructed and the composition isolated above was used to determine SOD, CAT, GSH-Px, MDA and Hyp content in the skin of mice by gavage method. The results showed that Lophius litulon skin collagen peptides had strong reducing power and O-2?, DPPH?, ?OH scavenging ability in vitro. When the sample concentration was 10 mg/mL, ?OH, DPPH?, O-2? free radical scavenging rate and reducing power were 70.48%, 68.78%, 42.53% and 0.676. The fraction relative molecular weight that had much better effect on ?OH free radical scavenging was less than 2 000 D components, and its IC50 was 15.7 mg/mL. The activity of SOD, GSH-Px, CAT in skin was increased respectively 20.9%, 41.3% and 58.1% at the dose of 100 mg?kg-1?d-1 collagen peptide, which significantly inhibited the formation of MDA compared with the model group in vivo.