Abstract: Nickel phthalocyanine (NiPc) Fe₃O₄ nanoparticles complexes were prepared and their chemical stability and magnetic property were measured. The results show that NiPc forms complex layers on the surface of Fe₃O₄ nanoparticles and there is somewhat chemical bonding between them. NiPc can protect Fe₃O₄ nanoparticles effectively from oxidizing and improve their antioxidation ability greatly. In addition, H c of NiPc Fe₃O₄ nanoparticles complex is much lower than that of Fe₃O₄ nanoparticles.