Abstract: With the cooling process, the solution in the pores of saline soil will undergo phase transformation. Theoretical analysis and experimental research are conducted on the salt crystallization behavior of saline soil during the cooling process. Firstly, starting from the thermodynamic theory, a theoretical expression for the initial crystallization radius of salt solutions in pores is given by considering the chemical potential equilibrium between phase transitions and the Young-Laplace equation. The relationship between the initial crystallization radius, temperature and initial salt content is analyzed. Secondly, a theoretical model is established to predict the content of pore solution and salt crystals, and the influence of temperature and salt content on salt crystallization behavior during the cooling process is analyzed through iterative calculations. Finally, the validity of the theoretical model is verified by conducting indoor cooling experiments on saline soil. The results show that saline soil is affected by temperature and salt content. As the temperature decreases and the initial salt content increases, the liquid saturation of saline soil decreases and the salt crystal content increases. The initial salt content has an important impact on the salt precipitation temperature of saline soil, and the salt precipitation temperature increases with the increase of the initial salt content. The salt swelling deformation of saline soil mainly occurs in the early cooling stage, and the amount of salt swelling deformation in the early cooling stage is greater than that in the late cooling stage.