Abstract: This study investigates the slope distress occurring between stations K303+129 and K303+259 of a highway cut. Field investigation, deep horizontal displacement monitoring, and performance testing of existing ground anchors reveal multi-level degradation across the slope, including shearing of inclinometer casings and stress-loss ratios of ground anchors exceeding 85%. The underlying mechanisms driving instability are analyzed in detail. The mechanical parameters of the slip surface were back-calculated using an inverse-analysis approach, and the slope stability and residual sliding force under natural and heavy-rainfall conditions were evaluated with commercial software Geo-slope. To address the identified defects, a combined remediation system comprising H-section micro-piles, ground anchors, and deep drainage holes was proposed. Post-treatment analyses show that the stability factor of safety increased from 1.044 to 1.233 under natural conditions and from 0.983 to 1.152 under heavy-rainfall conditions, demonstrating significant improvement. The findings provide a practical reference for the diagnosis and mitigation of similar slope-stability problems in highway engineering.