Abstract: An efficient aqueous two- phase based onC4mimBF4/ Mg SO4 extraction technique was developed to extract total flavonoids from Cynomorium Songaricum and evaluate the antioxidant activity. C4mim BF4concentration( %,w / w),Mg SO4concentration( %,w / w),and crude extract concentration( %,w / w) were selected as response factors,and the yield of total flavonoids was used as response value.The optimum conditions for total flavonoids extraction were obtained based on three- factor- three- level experiment design according to the principles of response surface methodology,and antioxidation activity was evaluated.The optimum conditions were13.025%( w / w),17.5%( w / w),and 12%( w / w) forC4mimBF4concentration,Mg SO4 concentration,and crude extract concentration respectively. Maximum yield of extracted total flavonoids from the experiments was determined to be 98.4% under the optimal conditions. The antioxidant property of total flavonoids was enhanced with the increasing of flavonoids concentration. Hydroxy radical scavenging rate and DPPH free radical reached65% and 67.2% respectively when total flavonoids concentration was 0.6 mg / m L.