In order to determine the optimum extracting process of the isoflavone from Dabie Mountain's Pueraria lobata and its reducing power, a 5-level, 4-factor Box-Behnken center-united experiment was conducted on the basis of single factor experiment. The Box-Behnken experiment analyzed and optimized the processing conditions by response surface methodology, and determined the reducing power of the Pueraria Isoflavone's extract under the optimum conditions. The results showed that the extraction rate of the Pueraria Isoflavone was 24.87%, of which the relative error was only 0.4% compared with the predicted value of 24.77%, under the optimum conditions of ethanol concentration 7.5%, liquid-to-solid ratio17.50 mL/g, treatment temperature 94.30°C, treatment time 47.36 min. The experiment also concluded that response surface methodology was suitable for the regression analysis of isoflavone's extraction rate and parameter optimization; the reducing power of Pueraria Isoflavone's EC50 value was 0.098 mg/mL.