Abstract: An aerobic denitrifying bacterial strain was loaded on nano Fe3O4 and applied to deal with actual living wastewater. The effects of free bacterial strains and immobilized bacterial strains for living wastewater treatment were compared. The optimum treatment conditions of free bacterial strains for wastewater are pH=6.8，30℃and 2 days of incubation time.，while those of immobilized bacterial strains are pH=7.8，30℃ and 3∶1 of Fe3O4/ dry weight of bacteria. The treatment effects of the bacterial strains are evidently improved by the immobilization on nano Fe3O4. The removal rates of total nitrogen，inorganic phosphorus and COD attained to 75.56%，38.83% and 87.5%，respectively. The bacterial strains loaded on nano Fe3O4 maintained high activities to remove total nitrogen，inorganic phosphorus and COD even repeatedly regenerated，which have broad application prospects in the area of nutrition –rich wastewater treatment.