Abstract: Taking the method of adding iron-carbon filler and denitrifying bacteria compound package to the urban river, the Fe/C micro-electrolytic coupling denitrifying bacteria aeration assisted in-situ reduction of contaminant in black-odorous river sediment and purification of water quality technology was constructed. The simulation experiment results show that when the iron-carbon filler is 30g/kg, the denitrifying bacteria inoculating amount is 15mg/kg, the aeration rate is 60ml/min, and the aeration time is 9h/d. After running for 28d, the removal rates of COD, NH4+-N, TN and TP were 85.7%, 98.6%, 65.7% and 96.4%, respectively. The COD, NH4+-N and TP indicators are stable to reach Class IV water standards for surface water. the removal rate of TOC in sediment was 48.8%; The BD-P and NaOH-P components increased significantly; the different transferable nitrogen in the sediment decreased significantly; the surface 5~10 cm sediment changed from dark black to light brown, and the coupling technology can reduce the contaminant in black-odorous river sediment and improve the water quality. In the coupled system, iron-carbon micro-electrolysis improves the biodegradability of complex organic matter in water and sediment, carbon removal efficiency is significantly enhanced, removal pathway of nitrogen is increased, phosphorus is adsorbed and precipitates are fixed in the sediment; Although the denitrifying bacteria added havent become the dominant species, they have an inducing effect on nitrogen removal; aeration increases the concentration of dissolved oxygen in water, improves the sediment habitat, activates the indigenous microbial activity of the sediment, and synergistically reduces contaminant in black-odorous river sediment and improves the water quality. . This study provides a theoretical basis for the in-situ reduction of contaminant in black-odorous river sediment and purification of water quality by iron-carbon micro-electrolysis coupled with denitrifying bacteria.