Abstract: The optimum conditions for the preparation of antioxidant peptides from mung bean by complex enzyme synergistic hydrolysis were studied,and the antioxidant activity in vitro was investigated. Degree of hydrolysis as indicators,on the basis of single factor experiment,the optimum hydrolysis conditions for the preparation of mung bean polypeptide were selected by L₉ (3⁴) orthogonal design using pH,temperature,substrate concentration,and enzyme concentration as experimental factors,its antioxidant activity was evaluated by scavenging DPPH free radicals,superoxide anion radicals and hydroxyl radicals. The results showed that the optimal reaction conditions for the synergistic hydrolysis of mung bean protein by complex enzyme were pH8.5,temperature 56℃,substrate concentration 8%,enzyme dosage 4%,and hydrolysis degree up to 33.95%. The antioxidant peptides obtained from mung bean had strong antioxidant activity to DPPH free radical,superoxide anion free radical and hydroxyl radical,which were 82.8%,76.82% and 56.85%,respectively. In the field of natural antioxidants and health food had a certain value of development and utilization.