Ecohydrological services support the UN Sustainable Development Goals (SDGs). Quantitative studies on the trade-offs and synergies of ecosystem services at various scales have increased; however, their spatiotemporal evolution affected by vegetation restoration over an extended time series at the regional scale remains poorly understood. In this study, the spatiotemporal characteristics of water conservation (WC), soil retention (SR), wind and sand prevention (SP), and carbon sequestration (gross primary productivity [GPP]) during 1982-2020 were analyzed in the Loess Plateau and six subregions. The spatiotemporal variations in tradeoffs and synergies among the four services were examined using Pearson correlation and spatial autocorrelation analyses. Finally, the evolutionary mechanism of trade-offs and synergies under the influence of vegetation restoration were investigated using the center of gravity shift model. The primary results indicated that four ecohydrological services increased overall in the Loess Plateau and six subregions after vegetation restoration, showing synergistic relationships. A significant increase was observed in the plateau gully, loess hilly, and rocky hilly areas. Trade-offs among these services weakened, whereas synergies overall strengthened under the effect of vegetation restoration in most subregions, with extremely significant synergies increasing in the plateau gully and loess hilly areas. These results align with the aims of strengthening synergies and reducing trade-offs between ecosystem services. Affected by vegetation restoration, the proportion of areas with synergistic relationships between the pairs of WC, SR, and SP in the Loess Plateau increased by 16.5%, 13.6%, and 12.4%, respectively. The center of gravity of the synergies between WC and SR, SR and SP, and WC and SP in the Plateau shifted northwestward, southeastward, and southwestward, respectively, after vegetation restoration. Attentions need to be paid to those areas displaying significant trade-offs among WC, SR, SP, and GPP to achieve the SDGs. The findings of this study would provide insights in enhancing sustainable utilization of soil and water resources and ecological management, and making ecology restoration decisions for watershed ecosystems.