Abstract:As for the engineering construction in permafrost regions,the change of local permafrost environment,induced by human events,influences permafrost much more than the climate warming. The settlement on south faced slope is usually more than that on north faced slope,as indicated that the thawing of permafrost under south faced slope is acuter. Based on observed data in Beiluhe test site of Qinghai-Tibet Railway,the difference in thermal state between south faced slope and north faced slope was analyzed. The results indicate that the difference of ground-atmosphere heat transfers between south faced slope and north faced slope is very obvious and the annual mean temperature at a 0.5 m depth on south faced slope could be higher than that on north faced slope by over 3℃. The higher temperature on south faced slope is greatly attributed to high temperature during winter time. The fact that the annual ranges of ground temperatures near embankment surfaces are all greater than those near nature ground surface shows that the ground-atmosphere heat exchange of embankment surface is beyond that of nature ground surface. This kind of difference in thermal state may result in asymmetric thermal regime in embankment,and underlying soil as well. As a result,possible unevenly transverse deformation may appear.