The East Qinling Mountains serve as a key national ecological security barrier and the core water source area of the Middle Route of the South-to-North Water Diversion Project in China, where vegetation restoration is a core measure for regional ecological conservation. However, existing studies have mostly focused on the individual hydrological characteristics of either the litter layer or soil layer, with limited understanding of their synergistic effects and the functional differences among typical restored vegetation types. In this study, we investigated the hydrological functions of the litter layer and 0~40 cm soil layer across seven vegetation restoration types (five forest stands, grassland and farmland control) in the upper Danjiang River Basin, southern foot of the East Qinling Mountains. Key hydrological indicators, including litter biomass, water-holding capacity, effective interception capacity, soil porosity, organic matter content, and water storage capacity, were measured and comprehensively evaluated. Furthermore, we explored the underlying mechanisms by which vegetation restoration enhances the hydrological functions of the litter layer and soil profile. The results showed that vegetation restoration in the East Qinling Mountains significantly altered the litter characteristics, with broad-leaved, coniferous and mixed forests exhibiting higher litter thickness and biomass than grassland and farmland. Litter water-holding capacity varied markedly across vegetation types: Pinus tabuliformis-Quercus variabilis mixed forest (Pt-Qvmf) and Quercus variabilis Blume (Qv) showed the highest 24 h water-holding rate, water-holding depth, and effective retention depth, while grassland had the lowest values. Litter water retention followed a logarithmic function with soaking time, and water absorption rate exhibited exponential decay, with the semi-decomposed layer showing stronger water retention performance. Vegetation restoration effectively improved the soil bulk density, porosity, and water-holding capacity, with more pronounced amelioration in the topsoil layer, and significant differences were observed among vegetation types. Comprehensive evaluation via the entropy weight method revealed that Robinia pseudoacacia L. (Rp) and Pinus tabuliformis Carrière (Pt) had the optimal integrated hydrological functions of the litter-soil profile, while grassland and Platycladus orientalis (L.) Franco (Po) performed the poorest. Structural equation modeling further quantified the driving mechanisms: soil porosity was the dominant direct driver of soil hydrological function, while litter biomass exerted an indirect effect through a significant serial mediation pathway via root biomass, soil organic matter (SOM), and aggregate stability, with the model explaining 83% of the total variance in soil hydrological function. This study provides targeted theoretical support and practical guidance for vegetation restoration, optimal tree species configuration, and forest ecosystem management in the water source area of the South-to-North Water Diversion Project.