Abstract: The chemical compounds of essential oil of Chinese medicinal herb,Siphono-stegia Chinensis Benth,have been analyzed by capillary GC/MS.Thirty five compounds have been identified and estimated They are(%):α-limonene(0.65),1,8-cineole(0.49),3-methyl bicyclo [2,2,2]-octanone(0.81),1 ,cis-2,trans-4-trimethyl-cyclopentane(0.54),l-hexanol(0.70),3-octanol(0.89),n-decanal(0.81),1-octen-3-ol(3.56),menthone(16.50),iso-menthone(0.76),benzaldehyde(0.40),linalool(7.48),pentyl-cyclopropanc(0.54),6-melhyl-(E)-3,5-heptadien-2-one(0.49),trans-caryophyllene(0.89),l-menthol(7.12),pulegone(3.13)α-terpineol(1.50),hexanoic acid(5.12),gcraniol(3.06),benzyl alcohol(3.02),phenethyl alcohol(1.61),1-phenoxy-2,3-propanediol(1.99),AR-methoxybenzaldehyde(0.49),γ-nonalactone(0.40),ccdrol(0.81),6,10-dimethyl-2-undecanone(7.4),eugcnol(0.81),guaiol(6.72),cudesmol(6.77),4-(t-butyl)benzenediol-1,2(2.42),dihydroactinidiolide(0.98),nootkatone(0.58),2,3-dihydro-bcnzofuran(2.54),ascaridolc(0.55),All of these compounds have not been found in the herb previously.