Aerobic denitrifying bacterial strains were loaded by nano Fe3O4 and applied to deal with actual living wastewater. The optimum conditions and treatment effects of free bacterial strains and immobilized bacterial strains were compared. The optimum treatment conditions of free bacterial strains for wastewater were pH6.8, 30degC and 2 days of incubation time. Those of immobilized bacterial strains were pH7.8, 30degC and 3:1 of Fe3O4/ dry weight of bacteria. After loading the bacterial strains by nano Fe3O4, the treatment effects were improved, evidently. The removal rates of total nitrogen, inorganic phosphorus and CODcr attained 75.56%, 38.83% and 87.5%, respectively. The bacterial strains loaded by nano Fe3O4 maintained high activities to remove total nitrogen, inorganic phosphorus and CODcr even though they were regenerated, repeatedly.