In order to reveal the rule of influence of freeze-thaw cycles and freezing temperature on physical and mechanical properties of expansive soil, the paper took NanYang expansive soil as test object,and carried out deformation measurement and unconfined compressive test under different freeze-thaw cycles and freezing temperatures. The results showed that the volume change for expansive soil samples under freeze-thaw cycle could be expressed as “frost shrinking and thaw expanding”,with the increase of times of freeze-thaw cycles,the amount of frost shrinkage and thaw expansion of samples intended to be stable,the different freezing temperatures could change the residual porosity ratio of the samples. The mechanical properties of expansive soil could be affected by freeze-thaw cycles intensively, especially in the first time. In process of freeze-thaw cycle, the stress-strain curves of expansive soil samples became thin increasingly, and its failure strain, unconfined compressive strength and elastic modulus decreased gradually. When freezing temperature is -10 ℃, the influence of freeze-thaw cycles on mechanical properties of expansive soils is the greatest.