Abstract: The strength change of expansive soil under wetting-drying cycles plays an important role in the slope stability analysis. Through wetting-drying cycle model tests on the expansive soil slope, direct shear tests on soil samples fetched from the slope surface after various wetting-drying cycles are performed, and it follows that the strength varies with the wetting-drying cycles. The stability of expansive soil slopes under wetting-drying cycles is simulated by means of the shear strength reduction technique in finite element analysis. The results show that the shear strength of expansive soils decreases with the increasing number of cycles, the cohesion of expansive soil decreases obviously and the friction angle keeps a stable value. Furthermore, the slope stability and safe factor decrease with the increasing number of cycles.