The ultrasonic-assisted extraction of total flavonoids from garlic was studied by single factor experiment and orthogonal array design,and the antioxidant activity of total flavonoids from garlic were also investigated. The results showed that ethanol concentration significantly affected the extraction yield of total flavonoids. The optimum extraction technology of total flavonoids from garlic was as following: ethanol concentration of 60%,extraction temperature 60 ℃,extraction time 60 min and ratio of solid to liquid of 1∶ 30( g∶ mL). The yield of total flavonoids from garlic under these conditions was 4. 213%. The antioxidant experiment results showed that the total flavonoids extract had certain scavenging capacity to hydroxyl free radical( ·OH) and superoxide anion free radical( O 2-·). The scavenging capacity of the total flavonoids extract to ·OH was higher than that of Vc at the same concentration,but weaker than Vc on the scavenging capacity to O 2-·.