Abstract:The methods of eliminating walls by enzymolysis and low osmosis were used to analyze the somatic cell chromosome number of four original species of Chinese medicine 'Xihuangcao’. The results showed that the chromosome number of Isodon lophanthoides (Buch.-Harn. ex D. Don) Hara is 2n=3x=36, possibly this is a triploid. However, the others, such as I. serra (Maxim.) Kudo, I. lophanthoides var. gerardiana (Benth.) H. Hara, and I. lophanthoides var. graciliflora (Benth.) H. Hara, belongs to diploid, which chromosome numbers are 2n=2x=24. The chromosome numbers of 4 species were reported here for the first time. Especially, the triploid population was first found, it would be as references for identification, genetic and breeding in original species of Chinese medicine 'Xihuangcao’.