Effective hydrolysis of feather waste by keratinase is an important way to develop high-quality alternative proteins for feed. It has been shown that the reduction of disulfide bonds is the key rate-limiting step in the hydrolysis of feathers by keratinases. However, the reductive activity of keratinase itself is low. In order to increase the reductive activity of the catalytic system, we screened endogenous disulfide reductase from Bacillus subtilis and constructed a synergistic catalytic system, KerZ1/yjbI-S2-P1, consisting of keratinase and disulfide reductase by co-expression optimization. The reductive activity and feather hydrolytic activity of the synergistic system were 5.67-fold and 5-fold higher than the original system. Feathers were hydrolyzed to a higher extent compared with the original system. The total amino acid and soluble protein concentrations in the products increased by 99% and 59%, respectively. This study provides a more environmentally friendly and efficient reduction capability for keratinase to hydrolysis waste feathers, and also demonstrates a new way of alternative protein feedstock mining.