Abstract: A series of volume measurement, constant water content isotropic compression, and true triaxial shear tests on intact expansive soils subjected to freeze-thaw cycles at different moisture levels are conducted to investigate the effects of freeze-thaw cycles on the deformation and strength characteristics of expansive soils. The study investigates the effects of freeze-thaw cycles on the volumetric strain, suction, and yield characteristics of expansive soils, and explores the influence of the intermediate principal stress on the strength properties of expansive soils subjected to freeze-thaw cycles. Results show that expansive soil with higher water content（w₀≥23.0%）exhibits “frost heave and thaw shrinkage” behavior, whereas soil with lower water content （w₀≤19.8%）demonstrates “frost shrinkage and thaw expansion” characteristics. The mechanical parameters of expansive soils (including suction and strength parameters) all decrease with increasing freeze-thaw cycles. Notably, the most significant deterioration occurs after the first cycle, while the parameters tend to stabilize after 5 cycles. Under varying numbers of freeze-thaw cycles, both the loading collapse (LC) and suction decrease (SD) yield lines remain nearly parallel, with the SD yield line forming an obtuse angle with the vertical axis. The plastic expansion region of the expansive soil’s microstructural void ratio, enclosed by the LC yield line, SD yield line, and coordinate axes, gradually shrinks with increasing freeze-thaw cycles. Both cohesion and the internal friction angle follow an exponential decay pattern. Cohesion attenuates rapidly and retains a relatively low residual strength (35%～61%), whereas the internal friction angle maintains a higher residual proportion (77%～82%), indicating greater stability. This model suggests that the freeze-thaw-induced degradation of soil strength is primarily attributable to the loss of cohesion. These findings can serve as a reference for the long-term stability analysis and freeze-thaw disaster prevention of expansive soil engineering in seasonally frozen regions.