Based on observed data of two monitoring sections in Beiluhe test site of Qing-Zang Railway, The characteristics of underlying ground thermal regime after constructing high embankment arc analyzed. Results indicated that permafrost table was raised, the underlying ground temperature increased after constructing embankment. The rising of permafrost table should be attributed to an obvious decrease in fluctuation of temperature at the depth of permafrost table due to the thermal resistance effect of high embankment. Constructing high embankment may cause considerable difference in thermal regime between shade slope and sunshine slope of embankment. The sunshine slope is the most violent heat-absorb surface, while the shade slope presents as a heat-discharge surface. As a result, the thawing extent of underlying permafrost may differ.