By way of combined field tests and lab tests

it was studied that the change of moisture of the soil body of the slopes with seasonal temperature

height of slope

varieties of plants on the slope surface

and specific locations of the slope

etc. It is shown that: during freezing of the soil body of the slopes

moisture moves towards the frozen zone; with deeper depth of freezing

change of water content tends to take place at deeper depth too; the herbaceous plants has better moisture absorption function than the grass family on slope surface; the strength of the soil body is affected by variation of water content of the slope and temperature of the soil body. When the temperature of the soil body of the slopes is higher than 0℃

the strength of the soil body is mainly affected by its water content. When the temperature of the soil body of the slopes is lower than 0℃

the strength is mainly affected by temperature. It is proved by triaxial test that: cohesion of the soil body of the slopes increases with increase of water content in the beginning

but starts to decrease with increase of water content when the water content reached a peak. The internal friction angle of the soil body of the slopes generally decreases with increase of water content. This study can provide basis for prevention and treatment of freeze-thaw destabilization of soil road cutting slopes of high-grade highways in seasonally frozen-ground region.