Abstract: In 1973—1976 and 1981—1982 Mr. Chen Yiyu and other members of Comprehensive Scientific Expedition of Qinghai Xizang (Tibetan) collected a large number of thermal Cyanophytes from hot springs of Xizang Plateau and Hangduan Mountain region. Identification work was completed in 1983 and five new species viz. Phormidium valderianum (Delp.) Gom. var. longiarticulatum Li, Homoeothrix lyngbybides Li, Hemmatoidea xizangensis Zhu et Li, Rivularia thernialis Li, Calothrix polymorpha Li. were published in Acta Phytotaxonomica Sinica 22(2) : 167—176, 1984.The present paper deals mainly with the characteristics of the distribution of bluegreen algae in the hot springs of these regions (table 1—4) and reprots a new variety.Based on the water temperature, the author divides the hot springs into four types: chliarothermes (18—28℃); euthermes (28—45℃); acrothermes (45—65℃) and hyperthermes (over 65℃).The blue green algae Jin the hot springs of these regions are not only rich in species, but also significant in their composition. Some thermal species such as Synechococ cus lividus Cop. Oscillatoria terebriformis Ag. and O.amphibia Ag. tolerate the same range of temperature as those living in the hot springs of Yellostone and Japan.