Whey protein peptides were prepared via enzymolysis，and the corresponding conditions were optimized by taking antioxidant activity and protein recovery as two indicators． Then，the enzymatic hydrolysate was separated and purified by means of column chromatography，and the molecular mass of the product was measured． The results indicate that (1) alkaline protease is more suitable for the enzymolysis than trypsogen，flavorzyme and papain，with an optimal substrate dosage of 4． 0%，an optimal enzyme dosage of 8000U/g and an optimal enzymolysis time of 4h; (2) fraction A obtained by DEAE-52 cellulose column chromatography exhibits the highest antioxidant activi-ty，with a reducing power value of 0． 3200 ±0． 0041 and a DPPH radical scavenging activity of 6． 58% ±0． 36%;(3) further separation of fraction A via Sephadex G-15 gel column chromatography helps to obtain fraction G with a DPPH radical scavenging activity of 6． 73% ±0． 083%; and (4) the main component identified from fraction G，which contains three amino acids (namely Lys，Leu and Ser)，is of a molecular mass of 378u．