Slope roadbed stability in permafrost regions of Qinghai-Tibet Railway is a potential threat to long-term operation. In evaluating slope roadbed stability, thermal stability is of first importance. Through measuring ground temperature at Anduo section for three years, ground temperature changes and the changing trend in the next 50 years have been analyzed. From the research, the conclusions are as follows: ① filling railway embankment makes permafrost temperature field redistribute; asymmetry of slope direction and geometric asymmetry make ground temperature field asymmetric; ② filling railway embankment causes artificial permafrost table of roadbed change and show asymmetric, which changes original thermal balance and makes slope roadbed in a state of dynamic thermal stability; ③ numerical analysis predictions show that in the first 10 years, artificial permafrost table has greater elevation and its asymmetry gradually increases. Beginning from the 20th year, permafrost will completely degrade, and thermal stability in the maximum thawing depth period is the worst in the forecast 10th year.