Abstract: In this work, the Shuangyang sika deer fresh foetus were used as raw materials to optimize the enzymatic hydorlysis conditions of fresh deer foetus polypeptides by single-factor experiment and response surface methodology. Ultrafiltration and gel filtration chromatography were used to separate and purify the polypeptide from fresh deer fetus. Then the antioxidant capacity of the deer fresh fetal poly was studied. The results showed that the optimal enzymatic hydrolysis process of fresh deer fetal polypeptide was as follows:The enzymatic hydrolysis temperature was 54.5℃, the pH was 7.0, the enzyme dosage was 5100 U/g, the degree of hydrolysis was 34.97%. There were 3 groups of polypeptide components were isolated and purified from the deer fresh fetal polypeptide components with molecular weights below 10 kDa which were named DFP1, DFP2 and DFP3.The results of antioxidant experiments showed that DFP1 had the strongest scavenging ability. The highest scavenging rates of·OH radical and O^- ₂ radical were 81.47% and 79.43%, respectively. In summary, the enzymatic hydrolysis process of deer fresh fetal polypeptide optimized by response surface method was convenient and feasible. The prepared polypeptide has strong antioxidant activity, which provides a theoretical basis for the full development and utilization of Shuangyang sika deer sources.