Abstract: This study aimed to optimize the ultrasonic- assisted extraction of polyphenols from dandelion using single- factor experiments and response surface methodology. The antioxidant activity of the extracted flavonoids was evaluated. The optimal extraction conditions were determined as follows: the time of ultrasonic- assisted extraction 37 min,ultrasound power 380 W,solid- to- liquid ratio 1∶ 48 g / m L and temperature 42 ℃.Under these conditions,the predicted and experimental extraction yield of polyphenols was( 3.68% ± 0.05%) and 3.72%,respectively.The good consistency indicated the mathematical model could fit experimental data well.Polyphenols compounds were extracted from the whole plants,leaves or roots of dandelions under the optimal conditions,and their antioxidant activities were evaluated and compared. The polyphenols extracted from both parts possessed high total reducing power. DPPH and hydroxyl free radical scavenging abilities. The antioxidant activity of different parts of dandelion was in the decreasing order: leave > whole plant > root.