Abstract: This study investigated the modification of loess structure and permeability using gelatinized cassava flour for energy-conserving and environmentally friendly anti-seepage engineering. The hydraulic properties, seepage resistance, and microstructural modification in modified loess were systematically assessed across three compaction levels(80%, 85%, 95%)through four methods: variable-head permeability tests, soil-water characteristic curve(SWCC)measurements, mercury intrusion porosimetry(MIP), and scanning electron microscopy(SEM)analyses. Results indicated that cassava-modified loess at 80% compaction achieved a saturated permeability coefficient of 1.35×10^-6 cm·s^-1. This represents a two-order- of -magnitude reduction compared to untreated loess and imparts superior seepage resistance relative to conventional 95% compacted untreated loess. The modification can reduce the dependence on high compaction. Modified loess also demonstrated enhanced moisture stability, effectively resisting excessive water absorption at high saturation levels while exhibiting slower dehydration rates under dry conditions. Microstructural analysis revealed three key modification mechanisms: (1)effective filling of macropores(≥ 10 μm)by cassava flour,(2)homogenization of pore size distribution, and(3)formation of an integrated"skeleton filling-micro particle adhesion" structure. These structural improvements contributed to enhanced matrix densification and optimized hydraulic performance. The findings demonstrate the feasibility of an eco-friendly solution for low-energy seepage control materials. This approach provides new insights for the development of low-energy, environmentally friendly anti-seepage materials, and demonstrates significant engineering reference value for geological disaster prevention, including soil erosion control and loess collapse mitigation.