Abstract:To investigate ultrasonic-assisted extraction of total flavonoids from lingonberry and its antibacterial activities. Using ultrasonic power， extraction time， solvent concentration and extraction time as factors， extrac－ tion yield of total flavonoids as indicator to optimize the extraction conditions of the total flavonoids from blue－ berry by orthogonal experiment， the antibacterial activity of flavonoids was investigated systematically. The op－ timal extraction conditions of total flavonoids of lingonberry were as follows： ultrasonic power 450 W， ultrasonic time 25 min， ethanol concentration 50 % ， solid -liquid ratio 1 ∶ 15 （g/mL），under above conditions， total flavonoids extraction rate was 29.87 mg/g. When the concentration（pH 2.8） of total flavonoids from lingonberry was 40 mg/mL， it had obvious antibacterial effect on Escherichia coli， Bacillus subtilis and Staphylococcus au－ reus with the inhibition zone diameter of 21.17， 26.67， 23.91 mm respectively. The minimum inhibitory con－ centrations （MIC） were 2.5， 2.5， 1.25 mg/mL respectively. The low pH of the total flavonoids contributed to some extend to the antibacterial activity of the flavonoids， after neutralization， the antibacterial activity de－ creased significantly. The yield of flavonoids from lingonberry was 29.87 mg/g， under acidic conditions， the flavonoids had significant effect on Escherichia coli， Bacillus subtilis and Staphylococcus aureus.