Abstract: This study was designed to use essental oil of Blumea balsamifera (L.) DCby microwave-assisted extraction. Effects of microwave power, extraction time and solid-liquid ratio were studied via the single factor methodologies, and then the extraction parameters was determined by Box-Behnken response surface methodology. In addition, Agar diffusion method and agar dilution method were used to see whether the extracted oil has antibacterial effect. Study results showed that optimized extraction parameters wasmicrowave power 450 W, extraction time 23 min and solid-liquid ratio 10 mL/g. An oil yield of 3.45% was obtained under such conditions.Essential oil had antimicrobial activity to five kinds of microorganism.The order of antibacterial activity was aspergillus flavus > aspergillus niger > staphylococcus aureus > escherichia coli > pseudomonas aeruginosa.