Abstract: Objective To study the anti-oxidant effect of total flavonoids from mango leaves in vitro.Methods The flavonoids were extracted by ethanol with ultrasonic from mango leaves,The spectrophotometry method was used to determine the content of the flavonoids and the anti-oxidant effect on hydroxyl radicals,superoxide anions and lipid peroxidation in liver and erythrocyte hemolysis were determined.Results The flavonoids content of mango leaves extracts was 38.35% and the extracts had scavenge effects on hydroxyl radicals and superoxide anions.The concentrations of extracts causing 50% inhibition of hydroxyl radicals and superoxide anions wee 2.973 9 mg/mL and 3.861 2 mg/mL,respectively.The extracts (1-10 mg/mL) significantly inhibited malondialdehybe and spontaneous lipid oxidation in mouse liver,and erythrocyte hemolysis induced by H₂O₂.And the inhibitory effect showed a concentration dependant relationship.Conclusion The flavonoids of mango leaves have effect of scavenging radicals and the anti-lipid oxidation and inhibition hemolysis of erythrocyte.