Abstract: This paper presents thc chemical constituents of the essential oil of Cyatho- cline purpurea (Buch.-Ham.) O.Ktze., which is a folk drug and widely used as antiphlogistic, styptic, insecticide, diuretic etc. in China. Twenty two compounds were qualitatively and quentitatively analysed from this essential oil on the basis of GC/MS/DS, showed in Table (1 ). Two of them were important components: thymohydroquinone dimethyl ether (I ) (ca. 70%), and thymyl iso-butyrate (II) (ca. 19%), which were separated by chromotography and determined by the data of IR, PMR, CMR and MS. The thymyl iso-butyrate was first isolated from plant.

Key words: constituents, essential, syathocline, purpurea