Abstract: The extraction technology of total flavonoids from peach blossom was studied by theaqueous two-phase system of ethanol and ammonium sulfate. On the basis of single factor experiments, response surface methodology was used to optimize the extraction process of flavonoids with the mass fraction of ammonium sulfate, liquid-solid ratio, extraction temperature and extraction time as independent variables and the yield of flavonoids as index. DPPH·, OH· and O₂⁻· free radical scavenging rates were used to evaluate the antioxidant capacity of total flavonoids from peach blossom. The results showed that the optimum extraction conditions were as follows: Mass fraction of ammonium sulfate 15.2%, extraction time 26 min, liquid-solid ratio 27.8:1(mL/g), extraction temperature 51 ℃. Under these conditions, the theoretical value and the verification value of flavonoids yield could reach 45.64% and 45.65%, respectively, which were very close to each other. The results of antioxidant experiments showed that the total flavonoids from peach blossom exhibited strong free radical scavenging ability. The DPPH· scavenging rate was 94.21% when the concentration of flavonoids was 0.56 mg/mL, and those of OH· and O₂⁻· were 91.23% and 80.65%, respectively, when the concentration of flavonoids was 0.672 mg/mL. The aqueous two-phase extraction process of total flavonoids from peach blossom optimized by response surface methodology was reasonable and applicable, the model could well predict the yield of flavonoids, and the flavonoids obtained with good antioxidant properties would be further developed and utilized.