Polyphenols from acorn seed was extracted by ultrasound-assisted two-phase aqueous system and through one-factor-at-a-time and orthogonal array design methods to optimize extracting condition.The results indicated that acetone concentration had significant influence on the yield of polyphenols,the influence of amount of(NH4)2SO4 and ultrasonic time and material-solvent ratio on the yield of polyphenols wasn't significant under the test range.The optimum conditions for the extraction of polyphenols were as follows,acetone concentration 80%,am...