The total flavonoids were extracted from grape seeds by the aqueous two-phase of ethanol-( NH4)2SO4. The effects of independent variables( the mass fraction of ethanol and( NH4)2SO4,mass fraction of crude extract,pH and mass fraction of NaCl) were evaluated by single factor analysis. A two-phase aqueous system of23% ethanol and 17%( NH4)2SO4was used to extract total flavonoids from grape seeds. Mass fraction of crude extract,pH and mass fraction of NaCl on the extraction efficiency of total flavonoids were explored by Box-Behnken experimental design. The optimal aqueous two-phase extraction conditions were mass crude extract 21. 3%,NaCl1. 97%,pH7. 2. The highest extraction rate was up to 98. 8%,which was very close to the prediction of 96. 4372%.In conclusion,the optimized process has good reliability.