Research conclusions: Construction of the Qinghai—Tibet Railway changed the original condition of the frozen soil permafrost along the railway and water—heat environment around the embankment of railway．At the same time，the annual fluctuation and perennial fluctuation of the air temperature influence the engineering status of the embankment． This paper analyzes the main influence factors on the stability of the embankment on slope in permafrost regions Mong Qinghai—Tibet railway，such as water，ground temperature，frozen ground type and direction and degree of the slope，and gives the negative influence of these factors on the roadbed．