Abstract: Iron-carbon interior electrolysis combined with Ipomoea aquatica was established to treat black and odorous water. The single factor experiment was adopted through variable-controlling to study the effects of different planting density, dosage of iron-carbon, dosage of ceramsite on denitrification. After 22 days, the removal rates of TN and NH₄⁺-N were 74.1% and 99.6% respectively and their contents were stabilized below (13.65±1.24) mg/L and (0.18±0.04) mg/L respectively under the suitable conditions of the planting density at 80 plants/m², the dosage of iron-carbon at 18 g/L and the dosage of ceramsite at 52 g/L. Besides the abundance and the diversity of microoganisms were increased, the dominant bacterial phyla being Proteobacteria, Firmicutes and Bacteroidetes and the dominant bacterial genera being Pseudomonas, Escherichia-Shigella and Diaphorobacter, enabling the microbial community to be more suitable for the removal of nitrogen. The synergistic mechanism of the coupled system included: iron-carbon interior electrolysis could generate H and Fe²⁺ as electron donor of autotrophic denitrification, radial oxygen loss in Ipomoea aquatica could promote the nitration reaction, biofilm of ceramic and rhizospheric microorganism could denitrify, and ceramsite could absorb nutrient. This study provided the basis for the treatment of black and odorous water with iron-carbon interior electrolysis combined with Ipomoea aquatica.