Abstract: An ultrasound-assisted process was optimized for the extraction of flavonoids from Lysimachia patungensis. Factors including ethanol concentration, ultrasonic application time and power, as well as material:solvent ratio were investigated. Based upon the single factor tests, the extraction was subsequently optimized by orthogonal experiments. It was found that, when 90% ethanol was used in a 1:30 on the material:solvent ratio for a 30-minute extraction with the assistance of 420 w ultrasound, a maximized extraction rate on total flavonoids of 3.48% could be achieved.