Abstract: It is for the first time that the fingerprint spectrum of essential oil of 19 species of Bupleurum genus is established by GC relative retention times, and according to the overlap ratio of peaks and eight strong peaks in the fingerprint spectrum, their comparative study is achieved. The results point out that the fingerprint spectrum, overlap ratio and eight strong peaks are different from each other in various species of the same genus. Hence, this method provides useful informations for identification of plant species and verification of new species. It is a development for application of GC in sample analysis of complex components. This method has some advantage as follows: easy to operate, standard compound unnecessary, high utilization ratio for chromatographic peaks and good comparison.