[Objective] To optimize the extraction conditions of total flavonoids from Hedyotis diffsua Willd.based on response surface methodology.[Methods] Single factor experiments were conduced to examine the effects of the ratio of water to Hedyotis diffsua Willd.,extraction temperature,extraction time,ethanol concentration and times of extraction on the total flavonoids yield.On basis of which,center-united experimental design and response surface methodology were applied to optimize extraction conditions of tota...