Abstract: To elucidate how water-saving and nitrogen-reducing practices regulate bacterial nitrogen metabolism pathways in the rhizosphere to control nitrogen loss, field plot experiments were conducted in the irrigation district of the Tumuchuan Plain from 2023 to 2024. Using local conventional water-nitrogen management (nitrogen application of 200 kg/hm² with irrigation of 450 m³/hm² at the bud stage) as the control, five treatments were established, combining deficit irrigation (300 m³/hm² mild deficit and 150 m³/hm² moderate deficit) with reduced nitrogen application by 25% (150 kg/hm², medium nitrogen) and 50% (100 kg/hm², low nitrogen) at the bud stage. Results indicated that compared to the CK treatment, both the mild water deficit (W1) and the 25% nitrogen reduction (N1) treatments demonstrated significant advantages in improving the rhizosphere soil environment and promoting root growth. The W1 and N1 treatments significantly increased oxalate and citrate content in the rhizosphere at both the bud stage and maturation, while also increasing root length density (RLD). Furthermore, the W1 treatment increased K⁺ content during the bud stage and Ca²⁺ content at the maturation, while reducing Na⁺ content during the anthesis. However, moderate water deficit (W2) combined with 50% nitrogen reduction (N2) significantly decreased Cl⁻ and SO₄²⁻ content in the rhizosphere during the bud stage but failed to significantly enhance the root surface area density (RSAD). Regarding bacterial community structure, the W1 treatment significantly increased the Chao1, Observed_species, and Ace indices of nitrogen-metabolising bacterial communities in the rhizosphere soil during the seedling stage, bud stage, Anthesis, and Maturation (P<0.05). However, the W2 treatment significantly reduced the Chao1 and Observed_species indices during the bud stage. Regarding nitrogen metabolism pathways, the N1 treatment during the anthesis significantly reduced the relative abundance of rhizosphere bacteria norB, nirK, and napA while increasing the relative abundance of nxrA, establishing a ‘high nitrification-low denitrification’ pattern that increased the risk of nitrogen loss from the rhizosphere soil at this stage. During the bud stage, water-saving and nitrogen-reducing treatments (W1, N1, N2) significantly reduced the relative abundance of rhizosphere bacteria nxrA, norB, nirK, and napA; The W1 treatment also significantly increased the relative abundance of rhizosphere bacterial nosZ (11.16%) during the bud stage. This not only controls nitrogen loss from rhizosphere soil at its source but also promotes N₂ reduction, thereby reducing the potential for N₂O greenhouse gas emissions. In summary, mild water deficit during the bud stage effectively reduces the risk of nitrogen loss from sunflower rhizosphere soils in saline-affected farmland, improves the rhizosphere ionic environment, and promotes plant root growth, delivering dual benefits of agricultural water conservation and environmental protection.