Abstract: The lateral thermal erosion of thaw lake may damage the stabilization of the nearby engineering. This study discussed the lateral transfer heat mechanism of the thaw lake, and a heat transfer model with phase change was used to predicte the temperature regime changes beneath the frozen soil roadbed and possible subgrade defects under the influence of the thaw lake. The results show that the thermal erosion of the thaw lake to permafrost roadbed is mainly affected by the annual average lake-bottom temperature and the distance from the roadbed to lake-edge. Supposing the lake area is constant, the impact of the thaw lake with a higher annual average lake-bottom temperature on the permafrost roadbed is more serious than that with a lower annual average lake-bottom temperature, and also is more obvious with the distance decrease from the roadbed to the lake-edge. These impacts mainly include the gradually warming ground temperature and the expanding talik area beneath the roadbed. However, the most thaw lakes have been experiencing a process of area expansion. If this factor is considered, the actual increase of ground temperature is higher than the forecast one, and the damage is more serious.