To explore the impact of nitrogen application rates on CO2 sequestration and emissions in peanut field under regulated deficit irrigation in Liaoning Province, a split plot experiment was conducted in lysimeter in 2018 and 2019 to study the effects of different irrigation regimes (full irrigation during the whole growth period (F) and regulated deficit irrigation at the flowering and pod filling stages (F)) and nitrogen application rates (0kg/hm2(N0)、50kg/hm2(N50)、100kg/hm2(N100)、150kg/hm2(N150)) on dry matter accumulation, carbon sequestration and peanut yield an so on in farmland. The results showed that the dry matter accumulation, carbon sequestration, and peanut yield under the D treatment were 7.59%, 15.08% and 7.16% (two years average) higher than that under the F treatment, respectively. Under the two irrigation regimes, the dry matter accumulation, carbon sequestration and peanut yield were increased first and then decreased with the increase of nitrogen application rates, and reached the maximum value at the 100kg/hm2 nitrogen level. From the seedling to the pod filling stage, CO2 emissions in peanut field was increased first and then decreased, and reached the maximum value at the flowering stage. Compared with the F treatment, D treatment significantly reduced the average CO2 emissions in the soil at the flowering, pod setting, and pod filling stages, and decreased the cumulative CO2 emissions during the entire growth period. Under the two irrigation regimes, soil CO2 emissions were increased with the increase of nitrogen application rates. Under the same nitrogen application level, D treatment significantly reduced the cumulative CO2 emissions during the whole growth period compared with F treatment. The cumulative CO2 emissions in the DN100 treatment were 7.51% (two years average) lower than that of the FN100 treatment. Under different irrigation and nitrogen treatments, the DN100 treatment had the largest carbon sequestration and peanut yield, and relatively lower CO2 emissions, which was the best combination for carbon sequestration and CO2 emission reduction in peanut farmland ecosystem.