Abstract: The HPLC of the 21 samples of Isodon amthystoides,I.nervosa and I.macrocalyx from different regions and parts were obtained.Based on the area and time of peak,the differences of the 21 HPLC were compared by the method of Principle Component Analysis (PCA).The results showed:(1) Though there are differences among the HPLC of 8 different populations of Isodon amthystoides,I.nervosa and I.macrocalyx,the differences aren't very obvious.(2) The intraspecific differences of HPLC spectra among the populations of Isodon amthystoides were more obvious than those among the three species,which indicate that different places affect the chemical compositions and these three species could be replaced each other as Chinese medicinal drugs to some extent.(3) It is practical to apply PCA on the basis of HPLC to show the differences of plant samples.

Key words: Isodon Kudo, Population, HPLC, PCA