Abstract: The polyphenols in taproot of Antenoron filiforme was extracted by ethanol reflux extraction, and the mathematical model of the yield of polyphenol with temperature, ethanol concentration, liquid ratio and time was established by response surface methodology.Through this model, the optimum extraction process parameters of polyphenols were determined, and their antioxidant capacity was evaluated by in vitro antioxidant assay. The results showed that the polyphenol extraction rate model had a good reliability, the optimized extraction conditions were extraction temperature of 83.7 ℃, ethanol concentration of43%, liquid to solid ratio of 30 m L/g and extraction time 149 min. Under these conditions, the polyphenol extraction rate was90.065 mg/g for the first extraction, and two times extraction could be as high as 93.380 mg/g. Polyphenols in Antenoron filiforme taproot had strong DPPH· and hydroxyl free radical scavenging activity, and their half inhibitory concentration ( IC50) were 0.175 mg/m L and 0.025 mg/m L, respectively.