[Objective] This study aims to systematically investigate the effects of ecological restoration duration on rill erosion characteristics and the evolution of soil physical and chemical properties on the slopes of open-pit coal mine dumps. It further explores the relationships between various rill erosion features and soil properties, which holds significant importance for ecological restoration and soil-water conservation in mining areas. [Methods] Using typical open-pit coal mine dump slopes as the research object, five slope plots with different restoration years were selected. Adopting a space-for-time substitution approach, the study analyzed changes in soil physicochemical indicators and morphological metrics of rill erosion, including rill density, width-depth ratio, dissection degree, and erosion amount. The influence of soil properties on rill development was also examined. [Results] Erosion intensity was most severe in the initial stage of restoration and gradually decreased in later stages. The erosion modulus declined from 11597.57 t·km?2·y?1 year to 5658.23 t·km?2·y?1 at 12 years. With increasing restoration duration, both rill density and dissection degree increased significantly. This indicates that while the control measures failed to completely suppress the expansion of the rill network, they effectively reduced the erosion intensity. The width-depth ratio of rills decreased by 21.50% over 12 years, and the morphology transitioned from wide-shallow to narrow-deep, reflecting the mechanical stabilizing effect of plant roots in enhancing soil shear strength and suppressing rill incision and lateral erosion. Regarding soil properties, the initial restoration stage was characterized by the loss of fine particles and enrichment of coarse grains, forming an erosion-induced coarsened layer. As restoration progressed, silt content increased more than fivefold, the coarse-grained phenomenon alleviated, surface soil bulk density decreased, and porosity and saturated water holding capacity significantly improved. Organic matter and available nutrient content peaked at 8 years and then stabilized. [Conclusion] This study preliminarily reveals the synergistic evolution trend of rill morphology and soil properties during the restoration of dump slopes and their interrelationship. Soil bulk density was identified as the primary factor driving erosion, while soil structure and nutrients were crucial for erosion resistance. The findings provide a theoretical reference for soil-water conservation and ecological restoration practices in mining areas.