Abstract: Under the background of global warming, permafrost along the Qinghai-Tibet railway was in a state of degradation, which would affect the stability of the railway. In order to solve this problem, the observation data was collected about permafrost upper limit along Qinghai-Tibet railway.The data of 2007 and 2015 was compared.The characteristics of permafrost upper limit of filling subgrade section was analyzed, The engineering measures to reduce the deformation of subgrade engineering was discussed. The results showed that the artificial upper limit of filling subgrade in permafrost region of Qinghai-Tibet railway had been raised,comparing with the observed data in 2007 and 2015. Because of the difference between the left and right sides of the sunward and shady slope, the difference of the artificial upper limit below the left and right shoulders was more obvious.The temperature-rise of permafrost is obviously degraded. Laying gravel on roadbed slope in permafrost region of Qinghai-Tibet railway is helpful to dealing with subgrade deformation caused by permafrost degradation caused by climate change.

Key words: Qinghai-Tibet railway, permafrost degradation, sunward and shady aspect, filling embankments, artificial upper limit