[Objective] The study aimed to discuss the chemical composition of the essential oil from the Salvia plebeia R. Brown and reveal its pharmacological effect further. [Method] The essential oil was extracted from the S. plebeia by steam distillation and then its chemical composition was analyzed by applying GC- MS technique. [Result] There were 49 ingredients that were separated in total and 31 of them were identified, accounting for 87 .31% of the total essential oil. The main chemical components of the S. plebeia essential oil were : 1 ,2 ,3 ,4 ,4a ,5 ,6 ,8a-octahydro-7- methyl-4- methylene-1- (1- methylethyl) - naphthalene ( 17 . 395%) , Caryophyllene ( 12 . 495 %) , [ s- ( E, E) ]-1-methyl-5- methylene-8- ( 1-methylethyl ) -1 , 6- Cyclodecadiene (11 .987%) , ( 1S- cis) -1 ,2 ,3 ,5 ,6 ,8a-hexahydro-4 , 7-di methyl-1- ( 1- methylethyl)- Naphthalene- (8 .843 %) , alpha .- Cubebene ( 7 .846%) etc . [Conclusion] The main chemical composition of the essential oil from the Salvia plebeian, analyzed in the test, was terpene and had some difference with the reported analyzing result, which maybe related with the production area and the picking season.