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Setting up an indoor freeze-thaw cycle experiment, with different initial soil water contents (15%, 20%, 25%), different salt contents (original soil, 0.2% NaHCO3), different biochar particle sizes (0~0.5mm, S treatment; 0.5~2mm, L treatment) and the untreated group (CK). The effects of soil pore structure changes on soil permeability and water and salt redistribution under different regulatory measures during freeze-thaw cycle were analyzed. The results showed that freeze-thaw induced soil pore expansion, aggregate fragmentation, soil saturated water conductivity (ks) increased, frozen soil saturated water conductivity (kfs) decreased. In addition, the increase of initial soil water and salt content would increase the damage of soil structure by freeze-thaw action, increase the expansion of soil pores and the change amplitude of ks and kfs after the freeze-thaw cycle, and aggravate the proportion of soil water and salt upward migration during freeze-thaw period. The application of biochar can reduce the expansion of soil pores and improve the stability of soil aggregates during freeze-thaw period. Compared with CK, the ks was decreased by 48.35% and 37.69% on average under S and L treatment, respectively, and the kfs was decreased by 55.44% and 78.55% on average under S and L treatment, respectively. At the same time, biochar treatment can reduce the moisture content of the upper soil (10cm) and increase electric conductivity value. The proportion of large pores and small pores in soil were the key driving factors of ks and kfs, respectively. It was showed that the application of 0.5~2mm biochar had the best effect on soil permeability and water and salt redistribution under freeze-thaw conditions. The research results can provide theoretical basis and technical support for the theoretical research system of water and salt transport in freeze-thaw soil.