The Loess Plateau, a region characterized by ecological fragility and geohazard susceptibility, is increasingly affected by intensified freeze-thaw cycling and shifting precipitation patterns driven by climate change, which significantly altering the regional soil-water environment and escalating disaster risks. Elucidating the hydraulic response of loess, a representative porous medium, under freeze-thaw cycling is crucial for predicting its structural response and seepage evolution in seasonal frozen soil regions. In this study, the effects of freeze-thaw cycles on seepage behavior were systematically investigated using laboratory permeability tests, scanning electron microscopy (SEM), and particle flow code (PFC) numerical simulations. Results indicate that during the initial freeze-thaw stage (0-3 cycles), the permeability growth rate (eta) peaked at 275 %, whereas it approached zero in the later stages (11-15 cycles). The freeze-thaw sensitivity coefficient (SFT) peaked at 1.0 after 11 cycles and subsequently decreased to 0.78 after 15 cycles. Both eta and SFT increased and decreased with increasing dry density, with the peak points shifting toward higher initial dry density. Microscopic analysis revealed that the freeze-thaw cycles increased damage to the pore structure, increasing the porosity growth rate from 9 % to 25.7 %. Numerical simulations demonstrated that the freeze-thaw cycles increased the number of particles with large displacements and led to an exponential decline in the average number of contact bonds. Following the freeze-thaw cycles, particle displacement increased exponentially with seepage frequency. The growth rate of minimum displacement was slightly higher than that of maximum displacement, and total displacement increased with seepage pressure and frequency. This study provides new insights into how freeze-thaw cycles alter the hydraulic properties of porous media, providing a theoretical reference for disaster prevention and engineering construction in seasonal frozen soil regions.