In order to investigate the effect of salt on water and salt redistribution in freezing process, unidirectional freezing tests of soils with different salt contents were conducted. Moreover, model tests with four different boundary conditions(freeze-thaw cycle，evaporation, radiation, and precipitation) were used to investigate the transfer mechanism of salt and water in saline frozen soil. The results indicated as follows：due to the existence of salt，moisture migration will be weaken in the soil during freezing，so that the frost heave was mitigated. As no salt crystallizes in the freezing process，only frost heave exists in NaCl soil. However，Na₂SO₄ is sensitive to temperature，both salt and ice may crystallize during cooling，resulting in frost heave and salt expansion in sodium sulfate soil. Besides，the permeability of soil was decreased by Na₂SO₄ crystals，thus the water movement was reduced. In Na₂SO₄ soil with high salt contents(e.g. 3.6%)，in-situ salt expansion and frost heave occur at the initial freezing process，and segregation heave is negligible. For the Na₂SO₄ soil with salt content 2%，the water and salt migration are also negligible in freezing-thawing process. Salt effloresces in the evaporation process，and surface soil salinity moves downward with water infiltration. Dry-wet cycle is the main cause of salt expansion，which has a stronger effect on salt movement than freezing process. Salt expansion exists at the soil surface，while frost heave is observed at freezing fringe. Finally，the water and salt transfer mechanism have been investigated，including the cause of salt expansion and frost heave.