OBJECTIVE： To e stablish modified aqueous two-phase extraction （ATPE） system of polyphenols from Archidendron clypearia. METHODS ：Taking the polyphenol content ，extraction efficiency and partition coefficient of A. clypearia as indexes ，the solid-liquid ratio ，ethanol mass fraction and ultrasonic time of ATPE system were selected by single factor tests . The aqueous two-phase extracts from different polar parts of A. clypearia was prepared. The modifier was selected by taking polyphenol content and antioxidant activity [IC 50 of 1，1-diphenyl-2-trinitrophenylhydrazine （DPPH）， 2，2′-hydrazine bis （3-ethylbenzothiazole-6-sulfonic acid ） diammonium salt （ABTS）] as indicators ，combined with the grey correlation analysis between polyphenols and antioxidant activity. The effects of modified ATPE system with different mass fraction （0-90％）of modifier on the extraction of polyphenols from A. clypearia were investigated and compared with traditional extraction technology （ultrasonic extraction and heating reflux extraction ）. RESULTS ：The optimal ATPE system included solid-liquid ratio of 1 ∶ 45， ethanol mass fraction of 40％，（NH4）2SO4 mass fraction of 11％，ultrasonic extraction time of 20 min，at room temperature. In 3 validation tests ，polyphenol content ，extraction efficiency and partition coefficient were （28.35±1.01）％（RSD＝3.56％，n＝3）， （98.87±0.19）％（RSD＝0.19％，n＝3）and 13.25±0.71（RSD＝5.39％，n＝3），respectively. The modifier was ethyl acetate. When the mass fraction of ethyl acetate in the ethyl acetate-ethanol mixed solvent was 70％，there was no significant difference in the content and anti-oxidant activity of polyphenols from A. clypearia of modified ATPE （P＞0.05）. The yield and transfer rate of it were si gnificantly higher than those of ultrasonic extraction and heating reflux extraction （P＜0.05）. CONCLUSIONS ：The modified ATPE system with better extraction yield and transfer rate than the traditional extraction technology is successfully established，which can extract polyphenols from A. clypearia 1048214903@qq.com in one step.