In order to analyze the influence of embankment construction on thermal regime of permafrost underlying the embankment, monitoring sections were set along the National Highway G214. In these sections, the thermometer holes were installed at the nature ground, the centre of embankment, left and right shoulder, and left and right side of slope toe. By using the method of field monitoring and numerical simulation, the long-term changes of thermal regime of permafrost underlying embankment along the National Highway G214 were investigated. The results show that after the construction of common embankment in the permafrost region, the permafrost ground temperature gradually rises up and the melting rate of permafrost beneath the embankment is accelerated. The time of initially melting is ahead of schedule and the time of completing freeze-back is postponed. For the K369+210 section, at the 8 m depth under the left side of road shoulder, subgrade center and right side of road shoulder, the ground temperature rises up with a speed of 0.040, 0.050 and 0.047 ℃ per year respectively, and the descending rates artificial upper limit are 16.82,25.36 and 16.73 cm per year, respectively. With the consideration of the rising global temperature, the ground temperature gradually rises up and the permafrost underlying the embankment is in a continuous degradation situation. The artificial upper limit drops into a larger range when the average annual ground temperature is higher. After 30 years of the embankment operation, the permafrost upper limit continues to decline, which will affect the normal serving of the embankment in the permafrost regions. Thus, some measures should be adopted timely to protect permafrost by actively cooling embankment and to avoid greater thaw deformation, ensuring the normal operation of the embankment.