Taking propolis as raw material, based on single factor experiments, orthogonal test was used to optimize the ultrasonic-assisted extraction of flavonoids, and antioxidant activity of the total flavonoids was studied. The results showed that the order of factors affecting the extraction was ratio of solid to liquid＞ethanol concentration＞extraction time＞extraction temperature; the optimum extraction technology 〖JP2〗was A2B2C2D2, namely ratio of solid to liquid 1∶30, ethanol concentration 80%, extraction time 20 min, extraction temperature 50 ℃, under the condition the extraction rate of flavonoids in propolis was 9.60%. Propolis flavonoids had obvious inhibition effect on hydroxy radical and superoxide anion free radical, with obvious dose effect relationship, namely the ability of eliminating free radical strengthened along with the increasing of ethanolic extract density. Flavonoids of propolis with addition amount of 0.15 mg/mL had good antioxidant activity in scavenging free radicals, which was better than natural antioxidant Vc.