Abstract: To elucidate the interaction mechanism between the antioxidant peptide KNFL from wakame seaweed and bovine serum albumin (BSA), as well as its protective effect against protein oxidative damage, this study employed multi-spectral techniques including fluorescence spectroscopy, synchronous fluorescence, and circular dichroism spectroscopy, combined with molecular docking methods. These approaches analyzed the binding characteristics, interaction types, and effects on protein conformation between KNFL and BSA. By constructing a KNFL-DPPH-BSA ternary reaction system, the study evaluated KNFL's inhibitory effect on DPPH radical-induced oxidative damage to BSA. Results indicated that KNFL-mediated fluorescence quenching of BSA exhibited static quenching behavior. The two form a ground-state complex with a molar ratio of approximately 1:1 and a binding constant K_A>10⁴ L/mol, indicating strong binding affinity. KNFL increased the polarity and reduced the hydrophobicity of the microenvironment surrounding BSA's tyrosine residues, decreasing BSA's α-helix content by 1.14%, suggesting a tendency toward loosening of the protein's secondary structure. Molecular docking results revealed that hydrophobic interactions and hydrogen bonds were the primary driving forces, with KNFL primarily binding within a hydrophobic cavity formed by BSA residues Lys-114, Lys-116, and Glu-519. In the ternary system, KNFL inhibited DPPH-induced oxidative damage to BSA by 12.8%, acting through dual mechanisms: Competitive occupation of BSA binding sites and direct radical scavenging. This study provides theoretical support for developing and applying algal antioxidant peptides as functional food ingredients.