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Field experiment was conducted in 2023 to investigate the effects of different straw returning methods with N fertilization on soil CO2-emission and carbon balance in black soil maize fields. The experiment included three straw return methods: straw leaving the field (S0, control), straw mulching returning to the field (S1), and straw rotary tillage returning to the field (S2), and two modes of N fertilization: regular N fertilizer application (N, 250kg/hm2) and no N fertilizer application (W, 0kg/hm2, control), totaling six treatments. The soil CO2-emission flux and the contents of soil organic carbon (SOC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) after maize harvest were measured under different treatments, and the relationship between soil CO2-emission and the contents of SOC, DOC, MBC were explored, and the carbon balance of black soil maize field ecosystem was analyzed. The results showed that the cumulative soil CO2-emissions in each treatment were S2N, S1N, S0N, S2W, S1W,S0W, and the cumulative soil CO2-emissions of S2N treatment were increased significantly by 70.31% compared with S0W treatment (P<0.05). Under the same nitrogen application mode, straw returning to the field effectively increased the contents of SOC, DOC, MBC. Additionally, the cumulative soil CO2-emissions were positively correlated with the contents of SOC, DOC, MBC. Under different straw returning methods and nitrogen fertilizer, the yield of maize in S1N treatment was the highest (13534.4kg/hm2), and the crop carbon emission rate was the lowest (0.122kg/kg). The carbon balance value of black soil maize field ecosystem under different straw returning methods and nitrogen fertilizer application were all positive, showing a strong carbon “sink”, and the carbon balance value and soil carbon sequestration potential of S1N treatment were the largest, which were increased by 13.12%~94.05% and 3.49%~25.32%, respectively, compared with other treatments. In summary, the results of this experiment suggest that straw mulching and returning to the field, in combination with conventional nitrogen application (S1N), can effectively achieve the goals of soil carbon sequestration, emission reduction, and increased crop yield in black soil corn fields.