The study investigates the antioxidant activity of chitosan (CS) and its water-soluble derivatives, including hydroxypropyl chitosan (HPCS), quaternary ammonium salt of chitosan (HACC), and carboxymethyl chitosan (CMCS). In vitro experiments show that all samples have significant scavenging abilities against DPPH, superoxide, and hydroxyl radicals, with HPCS exhibiting the highest activity. In vivo experiments in rats fed a high-fat diet demonstrate that CS and its derivatives reduce serum lipid peroxides (LPO) and free fatty acids (FFA) levels and increase superoxide dismutase (SOD) activity, with HPCS and HACC showing the most significant effects. The results indicate that chitosan and its derivatives can effectively act as antioxidants, with their activity potentially related to the molecular structure and functional groups introduced during modification.The study investigates the antioxidant activity of chitosan (CS) and its water-soluble derivatives, including hydroxypropyl chitosan (HPCS), quaternary ammonium salt of chitosan (HACC), and carboxymethyl chitosan (CMCS). In vitro experiments show that all samples have significant scavenging abilities against DPPH, superoxide, and hydroxyl radicals, with HPCS exhibiting the highest activity. In vivo experiments in rats fed a high-fat diet demonstrate that CS and its derivatives reduce serum lipid peroxides (LPO) and free fatty acids (FFA) levels and increase superoxide dismutase (SOD) activity, with HPCS and HACC showing the most significant effects. The results indicate that chitosan and its derivatives can effectively act as antioxidants, with their activity potentially related to the molecular structure and functional groups introduced during modification.