Abstract: δ-MnO2 hexagonal nanosheets were prepared by topochemical oxidizing method. By controlling pH=10，Fe3O4 particles were formed by coprecipiting Fe2+ and Fe3+ and deposited on the surface of δ-MnO2，then the Fe3O4/δ-MnO2 ferromag netic nanoparticles were synthesized.The effect of iron amount on the structure and crystallinity of Fe3O4/δ-MnO2 was studied. The obtained materials were characterized by the means of X-ray diffraction（XRD） and field emission scanning electron microscopy（FESEM） etc..The absorption behavior of Fe3O4/δ-MnO2 ferromagnetic nanoparticles on the methylene blue solu tion was studied.The effects of adsorbent amount，the initial concentration of methylene blue and adsorption time on adsorption efficiency were systematically analyzed.Fe3O4/δ-MnO2 nanosheets with hexagonal morphology were uniform，with the lateral edge of about 100 nm.This material showed excellent adsorption property to methylene blue，and the adsorbing capacity of about 2.7 mg/g as well as the removing rate of about 86.3% after adsorbing for 1 h.

Key words: Fe3O4/δ-MnO2；nanosheet；methylene blue；adsorption behavior