Abstract: In this article,the sandy Chrysanthemu was grown in the desert of Alashan Inner Mongolia and the chemical constituents of essential oil from petals and branches with leaves of them was extracted by steam distillation.The chemical constituents of essential oil were separated and identified by GCMS,and the relative contents of them were detected by norm alization method.Thirty eight compounds in the essential oil from the petals of sandy Chrysanthemuand thirty two compounds from its branches and leaves were identified.They amounted to 76.192% and 87.520% of their total compounds,respectively.The mainly chemical constituents of essential oil of sandy Chrysanthemum petals and branches with leaves are monoterpene hydrocarbons,sesquiterpene hydrocarbons and their oxo derivatives,but the compositions and contents of the two have obvious difference.By comparing with the data of other related literatures,the chemical constituents and relative content of Chrysanthemum indicum from Anhui，Fujian,Sichuan Province and Alashan are very different.

Key words: petals of sandy Chrysanthemum, branches and leaves of sandy Chrysanthemum, the method of steam distillation, GCMS