The distribution characteristics of permafrost along the Qinghai-Tibet Railway (QTR) are analyzed aiming to understand the special climate condition of the Tibetan Plateau. The railway can be divided into 15 sections by the topography and geomorphology, of which the characteristics and engineering geologic conditions are described. Studying the effect of environmental change, including climate change and engineering activities, on permafrost along the QTR and Qinghai-Tibet Highway indicates that the cutting excavation is one of the most important factors to disturb permafrost, which may lead to instability and slumping of slope, forming surface ponds and thermokarst lakes, result in slope cracking, collapse and slope toe softening, etc. Sand filling roadbed may give rise to warmer permafrost under the roadbed; the microclimate at two sides of roadbed plays an important role to increase surface temperature. Retaining water and drainage facilities also bring on decrease of the thawed depth of permafrost and the thawed roadbed and toe of slope. In sum, the single sand filling roadbed, cutting and surface engineering may lead to warmer permafrost obviously.