Generally, Bombyx mori silk dyeing is performed using acid dyes. However, the color fastness is alwaysunsatisfactory due to the weak binding forces under neutral conditions. In the present work, graft polymerization of α-lipoicacid (ALA) onto silk fibers was carried out using a two-step method. Briefly, ALA was grafted onto the silk fibers, followedby a reduction-oxidation process to form poly(α-lipoic acid) (PALA) on the fiber surfaces, aiming at improving theelectronegativity of fiber surface and realizing cationic dyeing. The results implied that the combined treatments promotedthe intermolecular crosslinking between fibroin chains, endowing the silk fiber with low zeta potential simultaneously. A thinsedimentary layer on the fiber surfaces was observed for the PALA-deposited silk fibers, companying with a significantincrease in the content of sulfur and O/N ratio, which verified the successful graft polymerization. The modified silk fabricexhibited improved dyeability, and the dyeing depth and color fastness was noticeably higher compared to that of theuntreated after cationic dyeing. Meanwhile, the newly-built intermolecular disulfide crosslinks imparted a detectable antiwrinkleeffect to the silk fabric. This study provides a facile strategy for modification of silk fabric with improved dyeingbehaviors and physical properties.