Abstract:The extracted and purified puerarin was analyzed for biological activity，and the content and structure were determined using high-performance liquid chromatography（HPLC）and infrared spectroscopy（IR）.The antioxidant activity in vitro of purified puerarin was evaluated by the scavenging method of free radicals.The antibacterial activity in vitro was determined by the filter paper method，and the minimum inhibitory concentration of puerarin was determined by the microplate reader.The results showed that after purification，the content of puerarin determined by HPLC was 62.03%，and the scavenging rates of puerarin to 2，2'-azinobis-（3-ethylbenzthiazoline-6-sulphonate） cation（ABTS+）free radicals，1，1-diphenyl-2-picrylhydrazyl（DPPH）free radicals，and hydroxyl radicals at a certain concentration were more than 80%.The antibacterial effect on six strains was in the sequence of Escherichia coli＞Staphylococcus aureus＞Salmonella＞Bacillus subtilis，but no bacteriostatic activity against Penicillium funiculosum and Aspergillus niger was observed.The minimum inhibitory concentrations of puerarin against S.aureus and E.coli were 8.5 mg/mL and 4.50 mg/mL，respectively，showing good in vitro antioxidant and bacteriostatic biological activities.