Abstract: The quantitative freeze-thaw damage analysis of expansive soils is of great practical significance for engineering in cold regions. In view of the unreasonable selection of strain model in the existing researches on soil damage model, the concept of natural strain is introduced. Based on the theory of Weibull statistics and strain equivalence, a natural strain damage model is constructed. Through genetic algorithm, the global optimization function of model parameters is further realized. With the test data of expansive soils after freeze-thaw cycles, the damage model is verified, and the freeze-thaw damage analysis of expansive soils is further carried out. The non-damage deformation and damage deformation are distinguished to further verify the rationality of the damage model. The results show that the natural strain damage model can simulate the stress-strain curve of expansive soils after different freeze-thaw cycles with high accuracy. The initial stiffness and macro-strength have negative exponential relationship with the number of freeze-thaw cycles, and the non-damage deformation and damage deformation have good correspondence with the test curves of lateral compression and triaxial compression.