Abstract: To effectively recycle waste animal hair from the tanning process, keratin should be extracted by using a reasonable method. In this work, based on the different disulfide bond cleavage mechanisms, the keratin samples were extracted from wool by using four kinds of methods, including sodium sulfide method, L-cysteine method, sodium bisulfite method and peracetic acid method, and assigned as K1, K2, K3, K4, respectively. The structure and properties of the four keratin samples (K1, K2, K3, K4) were investigated and compared, including extraction rate, sulfhydryl content, molecular weight, hydrophilicity, solubility, and antioxidant activity. The electrophoresis results showed that the bands of keratin K1, K2 and K3 were mainly concentrated in the range of 40-60 kDa, while keratin K4 exhibited no obvious protein band. The contents of free sulfhydryl group in K1 and K2 were at 48.3 μmol/g and 41.2 μmol/g, respectively, which were higher than that of K4 (2.0 μmol/g). Keratin K4 extracted by peracetic acid method contained more sulfonic acid groups, resulting in higher solubility and hydrophilicity than those extracted by the other three methods. Furthermore, all the extracted keratin samples showed good antioxidant activity. The above results indicated that although the keratin samples obtained by different proposed methods exhibited great difference in their structure and performance, they had application potential in the fields of biomedicine and cosmetics.