In order to explore the impact of optimized nitrogen application on the carbon and nitrogen footprint of spring maize farmland ecosystem under shallow buried drip irrigation in the Xiliaohe Plain, a 2-year continuous positioning experiment was used from 2019—2020 in the Agricultural High-tech Demonstration Park in Horqin District, Tongliao City, Inner Mongolia. The conventional constant nitrogen topdressing with flood irrigation was used as the control (CK). Two treatments were set up under shallow buried drip irrigation, constant nitrogen topdressing (T₁) and optimized nitrogen topdressing (T₂: 70% of constant nitrogen topdressing), to study the effects of different irrigation and nitrogen fertilizaiton methods on spring maize yield, economic benefits, carbon and nitrogen footprint. The results showed that compared with CK, the T₁ and T₂ increased the maize yield, while improved the economic benefits of farmland (P<0.05). Soil respiration CO₂ emissions were the main source of farmland carbon footprint, accounting for 43%~44%. Chemical fertilizers were the main source of carbon emissions from agricultural production materials, accounting for 36%~43% of the total carbon emissions from production materials; nitrogen fertilizer application is the input of nitrogen footprint, accounting for 93%~95%. The net carbon values of farmland ecosystem under shallow buried drip irrigation had no significant difference between T₁ and T₂ treatments, but compared with CK, both were increased by 23.79% and 32.67%, respectively. The carbon efficiency of T₂ treatment was the highest, which was significantly higher than T1 and CK treatments (P<0.05). The nitrogen balance in T₂ was the closest to zero, which was significantly lower than T₁ and CK (P<0.05). The effective nitrogen input level was the highest in T₂, which was significantly higher than T₁ and CK (P<0.01). On the whole, the optimized nitrogen topdressing T₂ treatment under shallow buried drip irrigation reduced the carbon and nitrogen emissions of the farmland ecosystem in the Xiliao River Plain, improved the carbon efficiency and the effective utilization of nitrogen input, and ensured the maize yield and economic benefits. It is the optimal water and nitrogen management strategy for spring maize in the Xiliao River Plain, taking into account the high yield, high efficiency and ecology.