Abstract：Block-stone embankment with cooling roadbed has effects on lowering permafrost temperature. However，effect variation of lowering permafrost temperature beneath block-stone embankment is a significant issue after block-stone layer is filled by sand or snow. The field experimental research on cooling permafrost temperature beneath open and closed block-stone embankments is developed to compare the change of permafrost temperature. The results show that extensive convection can be produced in the layer of block-stone for open block-stone embankment，but weak in the layer of block-stone for closed block-stone embankment. The different results from more extensive effect on cooling temperature for open block-stone embankment against that for closed block-stone show the superiority of open block-stone embankment. In view of soil temperature at the depth of 0.5–1.0 m beneath open and closed block-stone embankment，the difference is minor in summer，but large in winter，where the lowest temperature of soil beneath open block-stone embankment is about 5 ℃ lower than that beneath closed block-stone embankment. In view of effect depth of cooling temperature for the soil beneath embankment，the effect depth of cooling temperature is up to 6.0–10.0 m for open block-stone embankment，but is only about 1.5–3.0 m for closed one.
