Objective To explore the effects of water and nitrogen management on soil nitrogen metabolism enzyme activity and wheat nitrogen utilization under irrigation based on soil moisture.Methods The experiment adopted a two-factor split zone design, and the main plot was three irrigation levels, i. e. the relative water content of the 0—40 cm soil layer at jointing and anthesis stages of wheat was supplemented to 65% (W1), 75% (W2) and 85% (W3). The subplot was four nitrogen application rates, i. e. pure nitrogen 0 (N0), 150 (N1), 180 (N2) and 210 (N3) kg/hm². Soil nitrogen metabolism enzyme activity, nitrogen accumulation and translocation, nitrogen nutrition index (NNI), residual amount of nitrate-nitrogen, grain yield, water-and nitrogen-use efficiencies were measured and analyzed in two wheat growing seasons from 2022 to 2024.Results 1) Supplementing irrigation to 75% and applying 180 kg/hm² nitrogen (W2N2 treatment) could significantly improve the activities of soil urease and protease, reduce the activity of soil nitrate reductase, facilitated the transformation of soil nitrogen into crop absorbable forms. According to the results of variance analysis, the effects of irrigation level, nitrogen application rate and their interaction on soil nitrogen metabolism enzyme activity reached a very significant level (p < 0.01). In addition, W2N2 treatment significantly reduced the residual amount of nitrate-nitrogen in the 60—120 cm soil layer, and reduced the risk of soil nitrogen leaching. 2) Both W2N2 and W2N3 treatments could significantly increase nitrogen accumulation in vegetative organs, nitrogen translocation and grain nitrogen accumulation, and had the best NNI, which could meet the nitrogen requirements of wheat. The effects of irrigation level, nitrogen application rate and their interaction on NNI, nitrogen accumulation and transport of wheat reached a significant level (p < 0.01). 3) The highest grain yield could be obtained by W2N2 treatment, while further increasing water and nitrogen input had no significant effect on grain yield. Different irrigation levels and nitrogen application rates had significant effects on grain yield, and the interaction between the two factors reached a very significant level (p < 0.01). The decision coefficient of irrigation level and nitrogen application rate on grain yield was 0.313 and 0.485, respectively. 4) W2N2 treatment had high water-and nitrogen-use efficiencies, that would be easy to cause a significant decrease under continuous improvement of irrigation level and nitrogen application rate. The effects of irrigation level, nitrogen application rate and their interaction on water-and nitrogen-use efficiencies of wheat reached a significant level (p < 0.01). Compared with W2N2 treatment, the two-year average nitrogen fertilizer agronomic efficiencies of W2N3, W3N2 and W3N3 treatment were reduced by 13.02% to 26.34%, the nitrogen utilization rates were reduced by 9.77% to 23.64%, and the irrigation water use efficiencies were reduced by 2.88% to 38.10%.Conclusion The soil relative water content of the 0—40 cm soil layer at the jointing and anthesis stages of wheat supplemented to 75%, and nitrogen applied at 180 kg/hm² can significantly improve wheat grain yield, water-and nitrogen-use efficiencies, nitrogen accumulation, nitrogen translocation in vegetative organs and grain nitrogen accumulation, and have the best soil nitrogen metabolism enzyme activity and NNI. It is the optimal water and nitrogen management for wheat with high yield and high efficiency in the Huang-Huai-Hai region.