In this paper, the climatic regionalizatioi. of the Qinghai-Xizang Plateau is basedon the climatic data of 191 stations upto 1970, while these of the Xizang area, upto 1975.The temperature index is taken as the first criterion for regionalization. This in-dex includes the number of ≥10℃ days and the mean temperature of the warmest month. On this basis, Qinghai-Xizang Plateau is delimited into three climatic zones,i.e. plateau temperate, plateau subfrigid and plateau frigid. While the southern slopesof the Himalaya is distinguished separately into north tropical and subtropical mon-tane climatic regions.Aridity and annual precipitation are used as the second criterion for regionalization.Aridity is the ratio of the potential evaporation and the precipitation in which thepotential evaporation is obtained from the H. L. Penman’s formula. Based on this,climatic zone is distinguished into humid, sub-humid, semi-arid, arid and dry types.Finally, according to the integration of temperature and humidity index, Qinghai-Xizang Plateau is divided into 13 climate regions. The results of the climatic regiona-lization are shown in Fig. 3.