Abstract: Against the backdground of continuous global population growth and increasingly severe food security challenges, enhancing crop yields and nitrogen fertilizer utilization efficiency have become critical objectives for sustainable agricultural development. Deep fertilization, as a precise and efficient fertilization technique, can optimize nutrient distribution, improve root growth conditions, effectively promote crop growth, and reduce nutrient loss. To systematically investigate the effects of deep fertilization on crop yield, root development, and nitrogen fertilizer agronomic utilization efficiency (NAE), this study employed a meta-analysis method, utilizing data from 675 experiments across 86 literature sources published between 2000 and 2024, to assess the comprehensive impact of deep fertilization on crop yield, root growth and NAE. The results showed that compared with surface application or ≤5 cm (CK), deep fertilization significantly increased crop yield, root surface area, root volume, and NAE, with increases of 12.18% (95% CI: 10.93%~13.45%), 22.84% (95% CI: 22.03%~23.64%), 44.11% (95% CI: 42.90%~45.31%), and 39.68% (95% CI: 38.88%~40.4 9%). Fertilizer application depth, climatic conditions, and soil physical and chemical properties significantly influence the fertilization effect of deep fertilization, with 10~15 cm being the optimal deep fertilization. Further increasing the deep fertilization does not result in further increases in crop yield, root system indicators, or NAE. Under conditions of annual rainfall ≤800 mm and annual average temperature≤15 °C, deep fertilization is beneficial for increasing crop yield, root surface area, root volume, and NAE. The crop yield increase effect shows a significant positive correlation with rainfall, while the effects on crop yield, root growth, and NAE first increase and then decrease with annual average temperature, with the best improvement effect occurring around 16~20 °C. When soil total nitrogen content is 1~2 g/kg and organic matter content is 20~30 g/kg, deep fertilization achieves the best comprehensive improvement effects on crop yield, root surface area, root volume, and NAE. Increasing or decreasing total nitrogen and organic matter content results in varying degrees of reduction in yield and NAE effects.Additionally, in acidic soils, deep fertilization has better effects on root system growth and NAE improvement than in alkaline soils. In summary, deep fertilization promotes root growth, increases crop yield and nitrogen fertilizer utilization efficiency, and achieves synergistic improvements in crop yield and nitrogen efficiency. The optimal deep fertilization is recommended to be 10~15 cm, with more pronounced effects in soils with moderate nutrient levels and slightly acidic conditions. This study provides important theoretical basis and data support for the precise regulation and promotion of deep fertilization technology in different ecological regions.