Abstract: This paper mainly studied the extraction processof the volatile oil from Allium fistulosum L.,and developed GC-MS to analyzz the chemical composition,and studied the antibacterial activity.The ultrasonic time,the ratio of material to liquid and the extraction were investigated by single factor experiment and orthogonal experiment.The volatile oil of Allium fistulosum L. was identified by GC-MS and the antibacterial activity of the volatile oil was evaluated.The optimum extraction time were investigated by single factor experiment and orthogonal experiment.The volatile oil of Allium fistulosum L. was extracted by ultrasonic assisted steam distillation.The main chemical components of the volatile oil were technology of volatile oil from Allium fistulosum L. was ultrasonic 40 min,material liquid ratio 1∶3 and distillation time 3 h.In this way the actual extraction rate of volatile oil from Allium fistulosum L. was 0.042 96%.GC-MS identified many chemical constituent.42 main compounds were identified by NIST mass spectral library search,and the main substance was sulfur compounds.such as fluorocytosine,allyl isopropyl sulfide,propylene methyl sulfide,dimethyl trisulfide,dipropyl trisulfide,tetrasulfide,thiophenet,hiane and thiazoles.The antibacterial experiments showed that the volatile oil from Allium fistulosum L. had good activity on the 8 strains selected.The optimized extraction process makes the extraction rate increase.The antibacterial experiment showed that the volatile oil of Allium fistulosum L. had antibacterial effect.A large amount of sulfide was identified by component analysis,which might be an effective antibacterial ingredient.

Key words: Allium fistulosum L., volatile oil, GC-MS, antibacterial activity