Abstract: The flavonoids of tartary buckwheat seed were extracted in the aqueous two- phase system by ultrasonic cooperation to improve the efficiency of separation and purification. Fifteen different organic solvent / inorganic salt systerms were adapted to extract the flavonoids from tartary buckwheat,and the effects of solid- liquid ratio,ultrasonic time,ultrasonic temperature,mass concentration of ammonium sulfate and acetone on the partitioning behavior of flavonoids were discussed in detail,while the extraction conditions were optimized by response surface methodology( RSM).The results indicated that the acetone /( NH_4)_2SO_4 aqueous two- phase system had the best extraction effect. The optimum extraction conditions were as follows: liquid- solid ratio 46.65 g / g,ultrasonic temperature 44.75 ℃,mass concentration of ammonium sulfate 22.86%,the yield of the flavonoid was 20.01 ±0.26 mg / g at the optimum conditions. Compared with 80% ethanol extraction,there was no significant difference between flavonoid yield and rutin content,but the purity of flavonoids reached 62.35% with an increase of 38.86%,while the DPPH·and ABTS +·scavenging capacity was increased 22.52% and 43.82%,respectively.Therefore,the technique provide a more economical and quick method to extract flavonoids of tartary buckwheat seed,improve the research progress effectively.