Abstract: The essential oil of Pyrus Ussriensis Maxim nangguos peel was obtained by simultaneous distillation . The chemicalcomponents were separated and identified by GC/MS. The yield of essential oils of Pyrus Ussriensis Maxim nangguos peelwas 0.61% when extracted by simultaneous distillation. The experimental results confirmed the presence of 58 volatilecomponents when extracted by steam distillation. The experimental results demonstrate that the major components wereYlangene (25.46), a-Farnesene(16.11), 1,3,6,10-Dodecatetraene,3,7,11-trimethyl-(9.15), Bicyclo[2.2.1]heptan-2-ol,1,7,7-trimethyl-(2.97), aphthalene,1,2,3,4,4a,5,6,8a-octahydro-7-methyl-4-me-thylene-1-(1-methylethyl)(2.63),1,4-Cyclohexadiene,1-methyl-4-(1-methylethyl)(2.61), 1H-Ben-zocycloheptene,2,4a,5,6,7,8-hexahydro-3,5,5,9-tetramethyl-(2.84),Cartophyllene(2.08),Benzene,2-methoxy-4-methyl-l-(1-methylethyl)(2.07), Benzene,1-methyl-4-(1-methylethyl)(2.04), 1,6,10-Dodecatriene,7,11-dimethyl-3-methylene-(1.72), Cyclohexane,1-ethenyl-1-methyl-2,4-bis(1-methylethene) (1.44).

Key words: Pyrus Ussriensis , Maxim nangguos peel , Essential oil , GC/MS