Saline soils is porous medium whose thermal conductivity is affected by components and particle shape. However, the particle shapes in geomaterials are various, and the component and its content are in dynamic change as the soil varies between unfrozen and frozen state. In this study, based on the theory of multi-phase medium mixed geothermal conductivity, a new model is developed to explore the dynamic variation characteristics of the thermal conductivity of sulfate soils. The developed model is validated by comparing the experimental results against the calculated ones. Compared with the other two models, the new model is more reasonable and effective, especially in low temperature.