青藏高原是世界上海拔最高的高原,其平均海拔在4.000米以上,有相当大的面积在海拔5.000米以上,并有一系列的山峰高于6.000米。青藏高原又是世界上中、低纬度地带多年冻土厚度最大、分布面积较广、温度最低的地区。

The chief characteristics of the permafrost distributed along the Qinghai-Xizang Highway are discussed in this paper.The Qinghai-Xizang Plateau has the greatest area, lowest temperature and thickest permafrost in the middle-low latitudes of the world. The permafrost distributed and perched on this plateau occupies more than 60% of the total permafrost areas in our country.The distribution of the permafrost on this plateau depends chiefly on the elevation as well as the latitude and other geological and geographical factors.On this plateau, the solar radiation, which has an important effect on the heat balance of the ground surface, is so strong that the necessary conditions for the permafrost formation appear more strict than those in the high latitudes. The southern limit of the permafrost in the Da Hinggan Ling (Great Khingan) Region generallycoincides with the 0 - -1℃ isotherm of the annual mean air temperature, while alongthe Qingha-Xizang Highway, with the -2- -3℃.According to areal differentiation in the permafrost distribution, six regions may be recognized.Besides, in this paper we also analyze some of the distributive laws of underground ice and the cryogenic structure of the permafrost, recite several cryogenic phenomena and their distributive characteristics and briefly discuss the history of the permafrost development in this region.