In order to study the effect of structure of chelated peptides of Channa argus and antioxidant activity， the chelated peptides particle size， zeta potential， structure and antioxidant activity were analyzed. The relationship between structure and antioxidant activity were determined. The results showed that the particle size of calcium chelated peptides and iron chelated peptides were significantly smaller， but zinc chelated peptides were similar to that of the peptide. The absolute value of zeta potential of chelated peptide was higher than that of short peptide， and the structure of chelated peptide was more stable. The contents of hydrophilic amino acids and antioxidant amino acids were increased， and the highest content of antioxidant amino acids was presented in iron chelated peptides. The characteristic absorption peaks of the chelated peptides and the short peptide showed that the binding degree of the different ions to the short peptide and the amino group. Electron microscopic showed that ions and short peptides were adsorbed together， and the adsorption of iron chelated peptides was the strongest. DPPH， H2O2 and O2-· showed different antioxidant activity and reducing capacity of chelated peptides due to different structures. Antioxidant activity of iron chelated peptides was strongest， and other chelated peptides have stronger antioxidant activity than that of short peptides. Antioxidant activity of chelated peptide and chelated rate have positively correlated relationship.