Abstract: In the spring-thawing season,the reduction in shear strength at the freeze-thaw interface affects the stability of the slope. This paper studies the strength variation of fine-grained soil freezing-thawing interface. It carries out low-temperature direct shear tests at different freezing temperatures(-12 ℃,-7 ℃,-2 ℃),shear temperatures(-5 ℃,-2 ℃,1 ℃),and moisture contents(9%,16%,23%)respectively. In addition,according to the grey correlation analysis method,the paper determines and analyses the grey correlation of the factors. The test results show that the shear strength at the freeze-thaw surface decreases as the shear temperature and freezing temperature increase. The change of specimen strength is mainly related to the change of cohesion,and the change of internal friction angle is small. The order of the gray relational grade of the factors is water content>freezing temperature>shear temperature. The effect of ground temperature(freezing temperature) cannot be ignored when considering the effect of temperature on strength.