Abstract: In order to obtain Andrias davidianus peptides with high antioxidant activity,combined- enzyme( flavourzyme and neutral protease) is selected to hydrolyze Andrias davidianus muscle.The degree of hydrolysis was obtained,up to 44.12%.The extraction rate of Andrias davidianus peptides was about 90.28%.The hydrolysate was separated into 5 peptide parts by ultrafiltration membranes with 20,5,2,0.3 ku respectively,the DPPH·,·OH,and O-2·scavenging ability of the different parts were studied respectively.The results showed that the strength of different parts' antioxidant capacity was in the order: 0.3~2 ku peptides > 2~5 ku peptides > peptides below 0.3 ku> 5~20 ku peptides.0.3~2 ku peptides had the highest antioxidant capacity,of which the EC50 of DPPH·,·OH,and O-2·scavenging ability was 0.4,0.7,1.5 mg /m L respectively.So ultrafiltration membranes with 2 ku and 0.3 ku were applied in the Andrias davidianus peptides with high antioxidant activity.