Abstract: Objective Clarifying the impact and mechanisms of freeze-thaw action on hydrological erosion in the freeze-thaw zones of south-eastern Tibet is crucial for accurately quantifying erosion rates in high-altitude freeze-thaw zones and identifying the primary sources of eroded sediment. The findings of this study can provide a theoretical basis for regional soil erosion forecasting and the development and management of soil and water resources. Methods Three typical soil types—black felt soil, grass felt soil and dark brown soil—which constitute the largest proportion of the frost-thaw zone in south-eastern Tibet, were selected as the study subjects. The research combined laboratory experiments simulating the mechanisms of frost-thaw action with simulated erosion experiments in frost-thaw soil troughs. Results 1) Compared with the initial moisture content and freezing temperature prior to freezing, the number of frost-thaw cycles had a stronger influence on physicochemical properties such as soil porosity and aggregate formation.As the number of freeze-thaw cycles increased, soil porosity exhibited a trend of rapid initial increase during the first 1–3 cycles, followed by a gradual levelling off after 5 cycles. After 15 cycles, the relative increases in porosity for black felt soil, grass felt soil and dark brown soil were 1.79%, 1.03% and 1.70%, respectively; Aggregate changes exhibited a fluctuating trend, increasing during the first freeze-thaw cycle, decreasing thereafter, and showing an overall reduction. 3) Under identical conditions, erosion rates per unit flow were highest in grass-tufted soil, followed by black tufted soil and dark brown soil. Freeze-thaw action significantly increased soil erosion (P < 0.001), with the sediment yield per unit volume increasing by 1.12-fold, 1.35-fold and 2.46-fold in black tufted soil, grass-tufted soil and dark brown soil, respectively. Conclusion Freeze-thaw effect is a key driver to increase soil erodibility and intensified water erosion in the freeze-thaw zones of southeastern Tibet. Forecast and mechanism research on water erosion affected by freeze-thaw in high-altitude, cold regions should be strengthened. The findings of this study provide theoretical foundations for soil and water conservation, ecological protection, and sustainable development in high-altitude, cold freeze-thaw zones.