The Chaidaer-muli railway winds along the Datong River in the central region of the Qilian Mountains. The widely distributed permafrost along the railway is characterized by swampy and warm, which leads to the poor Engineering geologic conditions of the transportation line from the point of frozen soil. That the extending direction of the railway is nearly southeast-northwest causes its roadbed experience the yin-yang slope problems. To improve the stability of frozen soil roadbed, proactive cooling measures were adopted in a large proportion of the roadbed with permafrost, in which about 20km railway was equipped with thermosyphon. At the same time, different design parameter was adopted in the sunny and shady side slopes in the thermosyphon parts. Observation data in the experimental section with warm permafrost shows, under the condition of current thermosyphon techniques and design parameters, thermosyphon measures can effectively cool the frozen soil roadbed, substantially reduce the settlement and successfully solve the yin-yang slope problem of the railway subgrade in swampy warm permafrost.