Abstract: [Objective] Research on the impacts of future land use and land cover change (LUCC) and climate change (CC) on water-related ecosystem services (WRESs) is crucial for addressing water scarcity and ecological degradation. However, few studies have comprehensively analyzed the variations of WRESs under different climate and land management scenarios, with limited exploration of multi-scale uncertainties.[Methods] This study integrates the MRI-ESM2-0 climate model, the Future Land Use Simulation (FLUS) model, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to assess the combined effects of CC and LUCC on water conservation (WC) and soil erosion (SE) in Hebei Province, and to reveal their uncertainties across spatial and temporal scales. [Results] From 2024 to 2050, WC in Hebei generally exhibits an upward trend under both climate scenarios, increasing first and then stabilizing under SSP245, while continuously rising under SSP585. SE shows an overall declining trend, decreasing steadily under SSP245 but first increasing and then declining under SSP585. CC plays a dominant role in influencing WRESs, with contributions to WC and SE reaching up to 99.30% and 93.14%, respectively, although its influence gradually weakens over time. The contribution of LUCC to WC declines with time, while its effect on SE, though smaller, gradually increases. The uncertainty driven by CC is generally higher than that driven by LUCC, and the overall uncertainty decreases over time at all scales. [Conclusion] The water-related ecosystem services in Hebei Province are projected to show an overall trend of “enhanced water conservation and reduced soil erosion.”The synergistic effects of climate humidification and ecological protection will significantly improve regional hydrological regulation and ecological stability. Strengthening ecological restoration and implementing zonal management are key pathways to enhance regional water security and mitigate climate risks.