【Objective】Studies relating soil N availability to N₂O emissions commonly focus on NO₃^- and in some cases NO₂^-. Thus, less effort has been devoted to measuring soil despite its role as a central substrate in N₂O production. 【Method】In this study, two typical greenhouse vegetable soils (alkaline vs. acid soil) were selected to explore the influencing mechanism of NO₂^- on N₂O emission. Also, its association with the inorganic nitrogen transformation processes, gaseous emission (N₂O, N₂, CO₂), and the abundances and transcription copies of functional genes (amoA, nirK, nirS and nosZ) under anaerobic (0% O₂) and aerobic (21% O₂) conditions through in-lab incubation and real-time quantitative polymerase chain reaction (qPCR).【Result】The natural accumulation and tolerance of NO₂^- were higher in alkaline soil than in acidic soil. With respect to pH, the relative concentration of NO₂^- in soil did not correlate with N₂O emissions. However, the addition of NO₂^- significantly increased the N₂O emission and N₂O/(N₂O+N₂) index (I_N2O) of the two soils (P <0.05), and decreased the N₂ emission in both soils under anaerobic conditions (50.9% and 94.2% in alkaline and acidic soils, respectively). In the alkaline soil, exogenous NO₂^- at 60 mg·kg^-1 had no significant inhibition effect on soil CO₂ emission, and the transcription copies of nirK gene at 16 h under anaerobic incubation, amoA gene at 16 h and nirS gene at 84 h under aerobic incubation were significantly higher than that of control check (N0), but nosZ gene had no such phenomenon. In acid soil, the overall gene and transcription activity of amoA was low, and the transcription copies of the nirS gene increased with the increase of incubation time in aerobic N0 treatment (P <0.05). Exogenous NO₂^- at 60 mg·kg^-1 significantly reduced the CO₂emission, and the abundance and transcription copies of related genes in the acid soil. Oxygen significantly reduced the transcription copies of denitrification functional genes in both soils, and nirK was more sensitive. Compared with the N0 treatment under anaerobic incubation, the transcription copies of nirK, nirS and nosZ in alkaline soil were reduced by 97.3%, 74.5% and 89.0%, respectively, at 16 h under aerobic incubation. The variation trend of the denitrification genes transcription copies in both soils under aerobic conditions was different. In the alkaline soil, the transcription copies of denitrification functional genes were significantly decreased with the increase in incubation time (P <0.05). In the acidic soil, only nirK transcription copies decreased significantly with the increase of incubation time (P<0.05) in N0 treatment under aerobic conditions, while nirS and nosZ transcription copies increased, or decreased first and then increased, respectively. 【Conclusion】The accumulation of NO₂^- in soils will increase soil I_N2Oand affect the N₂O emission pathway by inducing nir gene transcription to compete for electrons with N₂O reductase and inhibiting N₂O reductase activity. These results provide a scientific basis for exploring the efficient utilization of soil nitrogen and N₂O reduction in greenhouse vegetable soils.