In order to solve the problem of roadbed packing in Linzhi area of Tibet,the silt is improved by cement in the area. The maximum dry density,the optimum water cut rate,the CBR value and the physical properties of the modified soil under different freezing and thawing cycles are studied by the compaction test,the CBR test,the unconfined compressive strength test and the frost heave sedimentation test. The results show that:The optimum moisture content of cement with different content is almost constant,and the maximum dry density increases slowly with the increase of content;Under the action of freeze-thaw cycle,the cement improved silt is still brittle failure mode,and the uniaxial stress-strain curve of the cement-modified silt is almost coincident,so in the actual project the strength of the cement frozen after 5 times can be taken as a modified soil design reference strength;Considering the effect of freeze-thaw cycle,the optimal cement content of the silt filler on the secondary road of Linzhi deep silty area in Tibet is more than 4%.