Abstract:To increase the utilization rate of moringa，the extraction conditions of total flavonoids in Moringa oleifera leaves were optimized and the antibacterial activity was studied.Using extraction efficiency of total flavonoids as evaluation index，the ultrasonic power，the time of ultrasonic-assisted treatment，ethanol concentration and liquid/solid ratio were investigated through single factor test and Box-Behnken response surface methodology to acquire the optimum extraction process.Meanwhile，the antibacterial activity of total flavonoids was evaluated through Oxford-cup test and serial two-fold dilution method by measuring the inhibition zone and minimal inhibitory concentration （MIC）regarding four tested microorganisms.The results indicated that the optimum extraction conditions were as follows：ultrasonic power was 400 W，the time of ultrasonic-assisted treatment was 35 min，ethanol concentration was 65%，liquid/solid ratio was 41 ∶1（mL/g），the extraction efficiency of total flavonoids reached 7.64%.The bacteriostatic study showed that the obtained total flavonoids had antibacterial capacity towards Candida albicans，Staphylococcus aureus，Bacillus subtilis and Escherichia coli of varying degrees，with MIC of 2.05 mg/mL for C.albicans，E.coli and S.aureus，and 4.10 mg/mL for B.subtilis.