Objective To optimize the ultrasonic/microwave assisted extraction method of Sophora tonkinensis Gapnep. flavonoids by genetic algorithm, and to study their antioxidant activies and antibacterial activities. Methods Used the flavonoid yield as index, the solid-liquid ratio, ethanol concentration, microwave power and extraction time were tested by single factor test and orthogonal test design, and the technological conditions was optimized by genetic algorithm. The scavenging rates of S. tonkinensis Flavonoids on 1,1-diphenyl-2-picrylhydrazyl radical(?DPPH), superoxide anion radical (O2-?)and hydroxyl radical (?OH) were tested to evaluate the in vitro antioxidant activities. The peroxide value(POV) of S. tonkinensis flavonoids on lard, peanut oil and corn oil were tested to evaluate the in vitro anti-lipid activities. And the antibacterial activities of S. tonkinensis Flavonoids on 7 species of common bacteria were evaluated by filter paper disc diffusion method. Results The optimum technological conditions were as followed：the solid-liquid ratio was 24.9:1(mL/g)，ethanol concentration was 87%, microwave power was 699 W, and extraction time was 3min. Under this conditions，the flavonoid yield was 10.38mg/g, which was 99.69% of the model predictive value. The antioxidant activity study showed that the S. tonkinensis flavonoids possessed good antioxidant activities, the DPPH?, O2-?and?OH scavenging rates were 96.38% 91.35% and 82.23% when the flavonoid concentration was 30礸/mL, respectively. The in vitro anti-lipid study showed that S. tonkinensis flavonoids could obviously slow down the oxidation rates of lard, peanut oil and corn oil in the test time range, the anti lipid oxidation were equivalent to BHT with the same mass fraction. The antibacterial activity study showed that the S. tonkinensis flavonoids had good antibacterial activities on 6 species of common bacteria, and the order of antibacterial activities was Staphylococcus aureus, salmonella, shigella, Bacillus subtilis, Escherichia coli and yeast, but the study also showed that the S. tonkinensis flavonoids had no antibacterial activity on Aspergillus niger in the test range. Conclusion To optimize the extracting technical conditions by genetic algorithm was more reliable and more closer to practical production. The S. tonkinensis flavonoids possessed good antioxidant and antibacterial activities, which could be use as natural antioxidants and preservatives for food.