Objective: GC-MS was used to analyze the volatile oil components in Yinhua Miyanling tablet to enrich the study of chemical composition and provide a theoretical basis for quality control.Method: The volatile oil were extracted with steam distillation method according to ChP（2010）.The chemical compositions were separated by GC capillary column chromatography

and the relative content of constituents were determined by area normalization method.The GC-MS analysis was performed on an Agilent 19091M-436 capillary column（0.25 mm×30 m

0.25 μm）.The inlet temperature was maintained at 280 ℃.The column oven was begun at 60 ℃

then programmed from 60 to 280 ℃ at 10 ℃·min-1

held for 12 min.Mass spectrometer conditions were: ionization mode

EI electron;energy 70 eV;ion source temperature 230 ℃.The mass selective detector was operated in the TIC mode

mass scan range

20-500 amu.Result: Thiry compounds were detected and 21 compounds of them were identified.And the compounds that the relative content was more than 5% were palmitic acid（34.15%）

ethyl palmitate（21.01%） and 1

5

9-trimethyl-12-（1-methylethenyl）-1

5

9-cyclotetradecatriene（10.81%）

（Z

Z

Z）-9

12

15-ethyl linoleate（7.71%）.Conclusion: The main components in the oil were palmitic acid

ethyl palmitate

ethyl linoleate ingredient.