Abstract: In order to study the antioxidant activity of corn peptide modified with different donors, the acid (succinic anhydride, acetic anhydride, acetic acid, citric acid, oxalic acid), sugars (glucose, lactose, galactose, mannose, fructose) and metal ions (ferric sulfate, copper sulfate, magnesium sulfate, zinc sulfate, manganese sulfate, calcium sulfate) were added to corn peptide as substrate.Donors were screened with Bacillus subtilis ls-45 as strain, and DPPH conversion rate was as index. The antioxidant activity of products modified by corn peptide with different doses (high, medium and low) after fermentation in vivo and vitro was studied. The results showed that, the effect of corn peptide modification femented by B. subtilis was as follows:Carbohydrate>acid>metal ion. The best donor of corn peptide chelate was glucose. When the feed ratio was 8:1, the conversion rate of DPPH reached 79.84%. The optimal modification product obtained after fermentation (corn peptide-glucose (CP-G)) was tested in mice for antioxidant activity. It was found that CP medium, high dose group and CP-G low, medium and high dose groups were significant (p<0.05) increased SOD activity in serum and liver. The low, medium and high doses of CP and CP-G significantly (p<0.05) increased serum GSH-Px activity, CP low, medium and high dose groups, CP-G medium and high dose groups were significant (p<0.05) Increased GSH-Px activity in the liver, which indicated that the corn peptide-glucose modified product after fermentation could effectively improve the antioxidant activity in mice.