Abstract: According to pridictions, the air temperature on the Qinghai-Tibet Plateau would increase with a value of 2.2~2.6℃. Therefore the pemafrost, featured by rich ice and high ground temperature, would continue the process of degradaion. Under such background, cooling principle was adopted in roadbed constructions of the Qinghai-Tibet Railway in permafrost regions. The engineering methodes of colling roadbeds are based on mechanisms of controlling convection, conductivity and radiation. After years of monitoring, it was indicateds that the methods are effective in protecting the undlying permafrost. Numerical simulations of the longtime efficiency showd that the methods would able to prevent the influence of the global warming. Though some methods need to be improved and optimized.