Abstract: The influence of the nano-bentonite content and water content on the compaction and anti-seepage performance of clay was investigated through compaction tests and variable head permeability tests.The optimal amount of bentonite was utilized to construct a bentonite-improved clay-gravel-clay capillary barrier system for simulated rainfall experiments.Vegetation cover and geosynthetic composite drainage net were introduced to study the impermeability effect of the bentonite-improved capillary barrier system under different conditions.The mechanism of moisture migration within the capillary barrier system in humid climate conditions was explored by analyzing response patterns of pore water pressure,volumetric water content,surface runoff and lateral drainage volume.The results show that 4% bentonite improved clay can serve as a fine-grained material capable of forming a capillary barrier effect with coarse-grained materials.Vegetation and geosynthetic network increase the duration for fine-grained materials to reach saturation,while also prolonging the effectiveness of capillary barrier effects.Vegetation enhances anti-seepage performance by reducing runoff volume,while geosynthetic network improves it by accelerating lateral drainage.Capillary barrier system exbits less responsive pore water pressure under brief and torrential rain compared to prolonged and light rain.