Abstract: In the present paper, the chromosome of 12 species in 11 genera of 7 famillies from the western Qinghai-Xizang Plateau were inverstigated in order to accumulate cytological data of this very species flora. Most of them are the dominant species to establish the plant communities of this region. Their karyotype formulas, and karyotype asymmtry following Stebbins's classification, are shown as follows: Chesneya nubigena (D.Don)Ali, 2n=16= 10m+ 6sm, 2Bi Caragana versicolor Benth., 2n=18= 14m+4sm, 2Bi Caragana gerardiana, 2n=18= 14m+4sm,2B;Dracocephalum heterophyllum Benth., 2n=24) Physochlaina praeslta,Kasing & A.M.Lu 2n=42=34m+8sm, 2Ai Lloydia serotina(L.) Reich.,2n=24=6m+ 10sm+8st, 3Bi Allium sikkimense Baker, 2n = 24 = 48 = 38m+6sm+4st,2A; Artemisia minor Jacq. ex DC., 2n=18=16m+2sm, 2A; Crepis flexuosa (Ledeb.)C.B.Clarke, 2n= 14=12m+2sm, 2Ai Microula tibetica Benth., 2n=24; Christolea crassifolia Camb., 2n=14=6m+6sm+2st.

Key words: Qinhai-Xizang