An effective and environment-friendly method for separating and concentrating baicalin from Scutellaria Baicalensis Georgi (SBG) extract by aqueous two-phase flotation (ATPF) was established. Using an aqueous two-phase system of polyethylene glycol (PEG)/ammonium sulfate, the effects of varying solution pH, (NH4)(2)SO4 concentration in aqueous solution, PEG molecular weight, nitrogen flow rate, flotation time and initial volume of PEG phase were investigated in detail. Under the optimal conditions for ATPF, the established method was successfully applied to the real sample, and the separation efficiency was more than 90%, and the concentration coefficient was more than 27. Compared with solvent sublation (SS), liquid-liquid extraction (LLE) and aqueous two-phase extraction (ATPE), ATPF showed advantages of good separation efficiency, high concentration coefficient and low consumption of organic solvent. All experimental results indicate that ATPF is an effective pretreatment technique for the instrumental purification of baicalin from SBG. (c) 2013 Elsevier B.V. All rights reserved.