The R&D and application of natural biomass resources is one of the important ways to solve the world’senergy shortage and environmental pollution. However, the complex processing technology and poormechanical properties seriously hinder the development of the biomass polymers. A kind of naturalantioxidant, alpha-lipoic acid, was used to modify wool keratin by grafting thiols in this study, so as toameliorated the physical properties of regenerated materials. The optimal process parameters and modification mechanism were explored. Research results indicated that grafting ratio of lipoic acid can reachmore than 13% and the polypeptide chains were more stretched in solution, when 30% lipoic acid wasadded into keratin solution at 40 !C with a reaction time of 2 h. In addition, lipoic acid grafted on thiolgroups can effectively weaken the intra- and intermolecular forces of keratin, this change made thearrangement of macromolecular chains more orderly. The physical structure of modified keratin becameuniform and compact, and the materials had obtained better thermal and mechanical properties. Thisresearch provided a novel and environment-friendly method for the modification technology of keratin,and it was beneficial to expand the application fields of biomass materials.