The Loess Plateau, known for its sensitivity to climate change and ecological fragility, has seen a surge in research on water yield and conservation at local and watershed scales. However, regional-level studies quantifying the water conservation function, especially in the context of climate change and vegetation restoration, are scarce. This study addresses this gap by quantifying the spatial and temporal changes in water conservation on the Loess Plateau from 1982 to 2020, using the InVEST model's water yield module. Pearson's correlation coefficient and the Geodetector methods were employed to analyze the impacts of climate change and vegetation restoration on the water conservation. The results indicate a stable trend in water conservation from 1982 to 2020. Following the implementation of grain to green program in 1999, the average annual total water conservation volume improved by 5% compared to those during the pre-2000 period, approximately 66.7% of the regions exhibited increased water conservation, with particularly significant increases in the Loess Plateau gully and Loess Hills gully areas, by 11.2% and 18.4%, respectively. The increased precipitation and decreased evapotranspiration both enhance the water conservation. Increased vegetation cover improves regional water conservation. The Leaf area index (LAI) was positively correlated with water conservation in most areas of the Loess Plateau (about 71.7%), showing the strongest correlation in the Loess Plateau gully and Loess Hills gully areas. The explanation degree of each influencing factor of water conservation was ranked as follows: precipitation > potential evapotranspiration > LAI. The interaction of precipitation, potential evapotranspiration and LAI was significantly stronger than that of a single factor, and the interaction between climate factors had the greatest influence on water conservation, indicating that climate change is the main influence on water conservation in the Loess Plateau region. In addition, the implementation of grain to green program in 1999 has significantly enhanced effects of LAI and precipitation on water conservation. After the implementation of the fallow-land reforestation project, the enhancemetn of the water conservation of the Loess Plateau was primarily attributed to increase in precipitation. In future ecological management, LAI should be controlled in a reasonable range, and moderate restoration of vegetation should be maintained to improve the water conservation of the watershed ecosystem, Preventing the decline of regional water conservation due to over-restoration of vegetation cover. The research results would provide important theoretical basis for formulating regional ecological restoration policies, improving sustainable utilization of water resources and water conservation, and protecting ecosystem functions in various river basins.