Abstract: The phase diagrams of （NH₄ )₂SO₄  or NaH₂PO₄+ethanol+water systems were developed by titration method.The effects of ultrasonic power,ultrasonic time and ratio of material to solution,on the extraction yield,were studied by single factor experiments and response surface methodology.The result showed that the optimal extraction conditions were （NH₄ )₂SO₄  concentration of 23% (w/w),ethanol concentration of 20% (w/w),ultrasound input power of 750 W,ultrasound time of 44.5 min,ratio of solvent to solid of 28 (g/g) and extraction temperature of 25  ℃.The extraction yield was 9.04 mg/g under the optimal conditions.The Procyanidins has a strong ability of scavenging DPPH,and the antioxidant capacity of procyanidins extracted from grape seeds using ultrasonic-assisted aqueous two-phase system significantly higher than that of general reflux extraction.The technology were stable and feasible.

Key words: ultrasonic-assisted, aqueous two-phase system, grape seeds, procyanidins, response surface methodology