Abstract: Ultrasonic extraction assisted with ethanol was used to extract the antibacterial components of wild Artemisia, and then agar- hole- diffusion method was applied to detect its inhibition ability to E.coli. The optimal extraction parameters could be obtained by measuring bacteriostatic circle diameter. The results showed that the optimum extraction conditions were: ultrasonic power 270 W, ultrasonic time 35 min, ethanol concentration 51%, extraction temperature 73℃, ethanol extraction time 6h, ratio of solid to liquid 1:15. With this condition, the E.coli inhibition zone diameter of wild artemisia antibacterial component was 2.62 cm, comparing with the theoretical prediction value 2.78 cm by the Regression Model analysis, the relative error was 6.5%.