[Objective] Dissimilatory nitrate reduction to ammonium (DNRA), a biological pathway converting NO₃^- to NH₄⁺, provides ammonium for rice uptake and microbial immobilization, resulting in N retention in paddy soils. Recently, the coupling between DNRA and Fe²⁺oxidation has been reported occurring in freshwater lake or estuary sediments. However, so far little has been reported on this process in paddy soil, and its potential key factors are practically unknown.[Method] Using ¹⁵N-tracing technique in combination with membrane inlet mass spectrometer (MIMS), an in-lab incubation experiment was performed to investigate the process of DNRA coupled to Fe²⁺ oxidation as affected by oxygen presence and carbon addition in two types of paddy soils (CS and TY).[Result] Results showed that the process of DNRA coupled to Fe²⁺ oxidation was found in both paddy soils, where the potential rate of DNRA increased from N 0.36-0.38 to 0.81-2.35 nmol·g^-1·h^-1 with Fe²⁺ addition rising from 0 to 800 μmol·L^-1. At the concentration of 800 μmol·L^-1 Fe²⁺, potential rate of DNRA was significantly higher in CS soil than that in TY soil, which was in consistence with differences between the two tested soils in nrfA gene abundance. Effect of oxygen presence and/or lactic acid addition on the process of DNRA coupled to Fe²⁺ oxidation varied in the two tested paddy soils. In TY soil, regardless of singly or in combination applied, oxygen presence and lactic acid addition significantly promoted potential rate of DNRA at varying Fe²⁺concentrations. In CS soil, single oxygen presence or lactic acid addition significantly increased potential rate of DNRA at the concentration of 500 μmol·L^-1 Fe²⁺, whereas, at the concentration of 800 μmol·L^-1 Fe²⁺, either lactic acid singly applied or in combination with oxygen significantly decreased potential rate of DNRA.[Conclusion] Findings of this study suggest that the process of DNRA coupled to Fe²⁺ oxidation occurs in paddy soils and may be affected by presence of oxygen and carbon addition. Further studies are needed to deepen understanding of this process by including more types of soil and comprehensively evaluating the effects of environmental parameters and soil properties on the process.