The main forms of cyanidin-3-O-glucoside (C3G) in various pH environments are different,leading to differences in its antioxidant capacity. Black bean protein,a common dietary protein, has the potential to serve as a carrier for unstable bioactive compounds. Understanding the interaction mechanism between black bean protein and C3G is beneficial for their application in food systems. Interactions between β-conglycinin(7S)and glycinin(11S)soybean proteins with C3G and their effects on the oxidative stability and antioxidant capacity of C3G at pH 2.0,5.0,and 7.0 were investigated using various spectroscopic analyses and molecular docking experiments. The results showed that binding of C3G with 7S and 11S at pH 2.0 and 5.0 not only reduced the hydrophobic environment around Tyr residues and increased polarity,but also increased α-helical content and decreased β-sheet content in both 7S and 11S. At pH 7.0,the presence of C3G led to an increase in both α-helical and β-sheet content in 7S and 11S except for β-turns. Furthermore,the binding of C3G with 7S and 11S was an exothermic process,and at different pH conditions,hydrogen bonding and van der Waals forces were the main driving forces for the interaction between C3G with 7S and 11S,resulting in static fluorescence quenching of 7S and 11S. Both 7S and 11S exhibited the highest affinity for C3G at pH 7.0. Molecular docking revealed that GLU229,ARG356,and PRO101 residues on 7S,and ARG161,VAL162,ILE171,and THR176 residues on 11S played key roles in the binding with C3G. Moreover,the binding of 7S and 11S with C3G significantly enhanced the oxidative stability and antioxidant capacity of C3G at different pH conditions.