Abstract: Objective:To study the extracting process of total flavonoids in the roots of Sanguisorba officinalis L.by using aqueous two-phase system. Methods :The effects of Triton X-100 concentration,ammonium sulfate concentration,crude extract concentration,Na Cl concentration and p H value on the extraction efficiency of total flavonoids were explored by one-factor-at-a-time and Box-Benhnken design methods. Results:The optimal aqueous two-phase extraction conditions were 15% Triton X-100,15% ammonium sulfate,crude extract mass concentration 12%,Na Cl concentration 0.5% and p H6. The forward extraction yields of total flavonoids reached80.02%. The optimal condition of backward extraction were as follows :butyl acetate 2m L,the upper phase1.5m L. The efficiency of backward extraction was 80.03%. Conclusion:This method was not only simple but also low-cost. Therefore it would have a well application perspective.