Abstract:A study hes heen made on the essential oil from the crude drug Peilan (Eupatorium fortunei) and the plants E. japonicum, E. chinense and E. cannabinum. 71 constituents have boon identified by GC-MS. Quantitative analysis has been carried out by GC. The study provides scientifie methods for the identification of the crnde drug "Peilan" and the quality control of the fresh and driod"Peilan".