Abstract:In order to search for new，effective and safe antibacterial drugs，the essential oil of Herba artimisiae sieversianae from Henan Province in China was extracted by steam distillation method and its chemical composition was analyzed by infrared spectroscopy and gas chromato graphy-mass spectrometry techniques.The results showed that 26 compounds which accounted to 85.05%of the total oil had been identified.The main components of them were caryophyllene oxide （15.24%），（+）-falcarinol（14.34%），（1R，7S，E）-7-lsopropyl-4，10-dimethy lenecyclodec-5-enol（8.90%），（-）-spathulenol（6.61%），n-hexadecanoic acid（5.72%），α-cadinol（5.19%）.The antimicrobial activity and minimum inhibitory concentration of essential oil from Herba artimisiae sieversianae were determined by filter Paper disk disffusion and spread-plate assay method.Results showed that the antimicrobial activitity of the essential oil against four tested microbes was different.The essential oil showed strong antimicrobial effect against Bacillus subtilis while weak effect against Bacillus cereus.The minimum inhibitory concentration （MICs） of the essential oil of Herba artimisiae sieversianae against Bacillus subtilis，Micrococcus tetragenus，Escherichia coli and Bacillus cereus were respectively 2.5，5，5 μL/mL and 10 μL/mL.Therefore，the essential oil of Herba artimisiae sieversianae could be used as a potential natural antimicrobial agent.