Abstract: Pueraia isoflavonoid was extracted with ethanol, methanol, 70% ethanol and water in different time by the method of ultrasonic wave, respectively. The constituents and mass fraction of the Pueraia isoflavonoid were determined by qualitative and quantitative analysis. The results showed that the optimum technological conditions of extracting Pueraia isoflavonid from Pueraria Lobata by the method of ultrasonic wave were:the extracted with methanol was 30min, the extraction yield in the optimum conditions was 20.6% with mass fraction 50.03%. It was a saving time and energy, convenient and efficient way to extract Pueraia isoflavonoid from Puerarin; m P. Lobata. by the method of ultrasonic wave. Meanwhile, the Antioxidative Effect of Pueraia isoflavonoid in the optimum technological Conditions was determined by the method of DPPH. Pueraia isoflavonoid has a stronger antioxidative effect and is a natural antioxdiant.

Key words: Pueraria , Lobata(Willd.)Ohwi , Isoflavonoid , Ultrasonic wave extracting , Antioxidative effect