Abstract: This study aimed to evaluate the effects of optimized nitrogen fertilizer management on greenhouse gas emissions in wheat/maize fields in the Huang-Huai-Hai Plain, while balancing crop yield and environmental sustainability.The traditional nitrogen application was set as the control group,and the experimental groups included reduced nitrogen application,organic fertilizer substitution,and inhibitors regulation.The impact of nutrient fertilizer optimization managements on greenhouse gas emissions in wheat/maize fields of the Huang-Huai-Hai Plain was quantitatively analyzed using the method of meta-analysis. The results showed that: Nitrogen reduction decreased CO₂ emissions by 10.32% and N₂O emissions by 29.34% in wheat/maize fields in the Huang-Huai-Hai Plain compared to conventional practices. CO₂ reduction exhibited a nonlinear positive correlation with nitrogen reduction ratios, showing greater efficacy in soils with pH > 6.5. N₂O reduction demonstrated linear correlations, achieving optimal results in soils with organic matter content of ≤20 g/kg and nitrogen input >300 kg/hm². A 20% nitrogen reduction was identified as the optimal threshold for balancing yield stability and environmental benefits.The contribution of factors affecting greenhouse gas emissions under reduced nitrogen fertilization was analyzed. The results showed that soil pH had the greatest impact on CO₂ emissions, accounting for 30.5%. The contributions of annual average precipitation and soil organic matter to CO₂ emissions under reduced nitrogen fertilization were 19.8% and 17.8%, respectively. The soil SOM content had the greatest impact on N₂O emissions, accounting for 24.5%. The nitrogen application rate was the second most important factor, contributing 20.8%. Organic substitution increased CO₂ emissions by 14.26% but reduced N₂O emissions by 15.97% in wheat/maize fields in the Huang-Huai-Hai Plain compared to conventional practices. CO₂ emissions showed linear increases with substitution ratios, particularly under conditions of annual temperature ≤13 ℃, organic matter content of≤10 g/kg, and nitrogen input >300 kg/hm². Conversely, N₂O reduction correlated positively with substitution ratios, achieving maximum efficacy in loam soils with annual precipitation ≤800 mm, temperature ≤13 ℃, and nitrogen input ≤200 kg/hm². A 0～30% substitution ratio optimized both emission reduction and yield enhancement. The factors contributing to greenhouse gas emissions under the condition of organic fertilizer substitution were analyzed. It was found that the soil SOM content had the greatest impact on CO₂ emissions, reaching 58.6%. The annual average temperature and crop type contributed 24.4% and 22.6% to N₂O emissions, respectively.Inhibitors regulation could significantly reduce N₂O emissions by 42.84% in wheat/maize fields in the Huang-Huai-Hai Plain. The N₂O emission reduction and production increase effect was in the order of nitrification inhibitor > combined application of urease/nitrification inhibitor > urease inhibitor. Among nitrification inhibitors, the effect of 3,4-dimethylpyridine phosphate was the best. The contribution of factors affecting greenhouse gas emissions under the control of inhibitors was analyzed. It was found that the type of inhibitor had the highest contribution to N₂O emissions, at 26.5%, while the contributions of nitrogen fertilizer application rate and soil organic matter content were both above 15.0%.The results of this study can provide an important reference for formulating optimized nutrient management measures for grain fields that balance high crop yield, soil fertility improvement, and greenhouse gas emission reduction.