Under the influence of both engineering activities and global warming, settlement is regarded as a heavy embankment disease in permafrost regions, which may result from many physical and mechanical processes, i.e., creep of unfrozen layers, thawing settlement due to the degradation (thawing) of the permafrost underneath, creep of warm frozen layers, freeze-thaw cycling of the active layer. In order to investigate the contribution of each physical and mechanical process to embankment settlement, settlement measuring devices were embedded in many sections with different geological and geomorphic conditions along the Qinghai-Tibet Highway. Through field observation, the physical and mechanical processes in embankment settlement, regarded as deformation sources, were analyzed. The result will have a great significance for revealing the settlement mechanisms of embankment and controlling the embankment diseases.