Abstract: Under agricultural intensification, excessive inputs of water and nitrogen fertilizers have led to severe over-extraction of groundwater in the North China Plain, resulting in a decline in the environmental carrying capacity of soil and other resources. Identifying the primary limiting factors of water and nitrogen in this region and optimizing the application of nitrogen fertilizers and irrigation are key strategies for improving crop yield and quality, as well as enhancing resource use efficiency in arid areas. This study focused on the widely cultivated high-quality strong-gluten winter wheat variety "Gaoyou 2018" in the piedmont plain of North China Plain. Four water treatments (W0, W1, W2, W3, with each increment adding 75 mm of water at the jointing, heading, and filling stages) and three nitrogen treatments (N250: conventional farmer practice, 250 kg N ha^-1; N200: 20% reduction; N150: 40% reduction) were established to investigate the effects of water-saving and nitrogen reduction on nitrogen translocation, water and nitrogen use efficiency, and grain quality in winter wheat. The results showed that compared to conventional irrigation, water-saving treatments significantly reduced yield by 16.9%–60.7%, primarily due to decreases in grain number per spike and thousand grain weight. Nitrogen reduction treatments significantly increased the average aboveground biomass (2.5%–21.6%) and harvest index (3.0%–16.0%) across different water-saving treatments. Water-saving treatments significantly enhanced nitrogen transfer rate in vegetative organs (10.1%–51.2%) and the contribution rate of nitrogen transfer amount to grain nitrogen (9.6%–131.8%), ultimately increasing grain protein content (10.9%–36.3%) but significantly reducing total protein content (7.6%–46.5%). Greater reductions in irrigation led to higher grain protein content but lower total protein content. Compared to N250, N150 and N200 reduced grain protein content (0.6% and 2.5%) but significantly increased total protein content (6.2% and 8.3%). Compared to W3, water-saving treatments significantly reduced nitrogen use efficiency (18.8%–61.0%) and nitrogen partial factor productivity (16.7%–60.3%) but significantly increased yield (3.1%–38.2%) and water productivity at biomass level (41.85%–93.4%). Yield was significantly positively correlated with nitrogen use efficiency, total protein content, thousand grain weight, and nitrogen partial factor productivity. The contribution rate of nitrogen transfer amount to grain nitrogen was significantly positively correlated with grain protein content, water use efficiency at yield level (WUEy), and water use efficiency at biomass level (WUEbm). Comprehensive analysis revealed that the W3N150 treatment scored the highest (2.94), with significant differences among irrigation treatments but no significant differences among nitrogen treatments. Therefore, water-saving treatments can be considered the primary limiting factor in this region, while nitrogen reduction treatments serve as a key strategy for reducing inputs, providing important guidance for dual-reduction strategies in the area.