[Objective] To determine chemical components of volatile oils from leaves of Artemisia argyi and study their antioxidant activities in vitro. [Methods]Volatile oils were extracted from leaves of Artemisia argyi by the steam distillation( SD) method and chemical components were analyzed and identified by gas chromatography-mass spectrometry( GC-MS) method. Through the method of scavenging DPPH( 1,1-diphenyl-2-picrylhydrazyl) organic free radicals,functions of volatile oils scavenging free radicals were studied. Ultraviolet-Visible Spectrophotometry was applied to determine and compare the clearance rate of volatile oils,antioxidant BHT( 2,6-Di-tert-butyl-4-methylphenol) and Ve( Vitamin E). [Results]40 chemical compounds were detected in volatile oils of leaves of Artemisia argyi. 27 of them were preliminarily identified,accounting for 89. 12% of total volatile compounds. Major compounds were thujone( 25. 17%),eucalyptol( 23. 42%) and alcanfor( 8. 58%),α-Thujone( 7. 76%),terpinen-4-ol( 4. 7%),and borneol( 3. 34%). Antioxidant activity in vitro experiment indicated that the ability of scavenging DPPH free radicals is BHT > volatile oils of Artemisia argyi > Ve. [Conclusion]Volatile oils of Artemisia argyi mainly consist of ketones and terpenes,which have excellent in vitro antioxidant activity. [Objective] To determine chemical components of volatile oils from leaves of Artemisia argyi and study their antioxidant activities in vitro. [Methods] Volatile oils were extracted from leaves of Artemisia argyi by the steam distillation (SD) method and chemical components were analyzed and identified by gas chromatography-mass spectrometry (GC-MS) method. Through the method of scavenging DPPH (1,1-diphenyl-2-picrylhydrazyl) organic free radicals, functions of volatile oils scavenging free radicals were studied. To determine and compare the clearance rate of volatile oils, antioxidant BHT (2,6-Di-tert-butyl-4-methylphenol) and Ve (Vitamin E). [Results] 40 chemical compounds were detected in volatile oils of leaves of Artemisia argyi. 27 of them were preliminarily identified, accounting for 89. 12% of total volatile compounds. Major compounds were thujone (25. 17%), eucalyptol (23.42%) and alcanfor (7.66%), terpinen-4-ol ( 4. 7%), and borneol (3. 34%). Antioxidant activity in vitro experiment indicated that the ability of scavenging DPPH free radicals is BHT> volatile oils of Artemisia argyi> Ve. of ketones and terpenes, which have excellent in vitro antioxidant activity.