Nano-zero-valent　iron　(nZVI),　as　a　typical　nano-material,　has　been　recently　used　in　wastewater　treatment　and　combination　with　bioreactors.　Using　nZVI　coupled　denitrification　system　research　the　effect　and　influence　of　nZVI　enhanced　denitrification　sludge　on　the　degradation　of　toxic　compounds　and　system　performance.　The　nZVI　coupled　denitrification　system　showed　better　resistance　to　2,6-DCP　impact,　and　the　concentrations　of　effluent　NO2-　and　NO3-　were　below　2.0　mg/L.　At　the　same　time,　the　addition　of　nZVI　enabled　the　denitrification　system　to　quickly　adapt　to　the　toxic　environment　of　2,6-DCP　within　15　days,　and　the　degradation　efficiency　of　2,6-DCP　reached　99.9%.　The　released　SMP　reduced　after　nZVI　coupled　with　denitrification　sludge　in　2,6-DCP　environment,　which　could　improve　the　effluent　water　quality.　Nuclear　magnetic　resonance　spectroscopy　showed　that　the　addition　of　nZVI　would　change　the　structure　of　EPS　in　denitrification　sludge.　After　90　days　of　operation,　the　dominant　bacteria　in　the　denitrifying　sludge　have　undergone　great　changes.　Moreover,　Thauera　was　responsible　as　the　dominant　bacteria　for　degrading　2,6-DCP　in　the　denitrification　system.　The　increased　in　the　proportion　of　functional　bacteria　with　nitrate_reduction,　nitrogen_respiration,　nitrate_respiration　and　nitrite_respiration　in　the　presence　of　NZVI　further　reveals　the　mechanism　of　enhanced　denitrification.