Anaerobic bottle experiments were operated in parallel for 160 consecutive days for raw (R-1), Polyurethane (R-2), and Fe3O4@Cu/Polyurethane (R-3) biodegradation of selected nitrogen-heterocyclic (NHCs) in coal gasification wastewater. The addition of Fe3O4@Cu/Polyurethane absolutely had an enhancement of microorganism for the degradation of NHCs. The results of GC-MS showed that the first step of anaerobic degradation of NHCs was the opening of nitrogen heterocyclic ring, the second step was the release of ammonia nitrogen and the opening of benzene ring. In R-3, direct interspecies electron transfer (DIET) guided by Fe3O4@Cu could realize the rapid transfer of electrons and avoid the accumulation of electrons in the degradation of the NHCs. Furthermore, acute toxicity analysis showed that under the enhancement of Fe3O4@Cu/Polyurethane, the selected NHCs was degraded effectively and the toxic inhibition of selected NHCs on living organisms decreased effectively. Finally, high-throughput 16S rRNA pyrosequencing showed that the dominant strains were dispersed more balanced with the assist of Fe3O4@Cu/Polyurethane.