Abstract: To clarify the effects of different vegetable rotation systems and fertilization treatments on nitrous oxide (N2O) emissions from farmland, this study established four rotation systems: system A (maize–broccoli–cabbage), system B (legume–broccoli–cabbage), system C (melon–broccoli–cabbage), and system D (fallow–broccoli–cabbage). Three fertilization treatments were applied under each rotation system: no fertilization (CK), conventional fertilization (CON), and 25% organic substitution (BMP). A two-year in situ monitoring experiment of soil N2O emissions was conducted from July 2023 to June 2025, during which soil environmental factors in the vegetable field were also monitored.The results showed that under different fertilization treatments, N2O emission fluxes ranged from -5.43 to 203.82 mg/m²/day, while the cumulative N2O emissions over the two-year period ranged from 6.15 to 108.16 kg/hm². Multiple emission peaks occurred within one crop growing season under all rotation systems, and the peaks generally appeared 1–6 days after fertilization. Correlation analysis showed that N2O emission flux was significantly positively correlated with soil water-filled pore space and electrical conductivity.N2O emission flux and emission intensity varied among rotation systems. The lowest cumulative N2O emissions under CON and BMP treatments were observed in system D. Under CON treatment, system A had the lowest emission intensity per unit nitrogen input, whereas under BMP treatment, system D had the lowest value. The emission factors of system D under CON and BMP treatments were also the lowest, at 2.45% and 1.08%, respectively.The effect of 25% organic fertilizer substitution for chemical fertilizer on N2O emissions from vegetable fields differed among rotation systems, while no significant difference in crop yield was observed between CON and BMP treatments. Compared with CON treatment, the total cumulative emissions under BMP treatment increased by 7.63% and 14.08% in systems A and B, respectively, but decreased by 2.56% and 50.52% in systems C and D, respectively.In conclusion, under the conditions of this experiment, the application of 25% organic fertilizer substitution for chemical fertilizer in systems C and D could reduce N2O emissions from vegetable fields while maintaining vegetable yield.