A magnetic MFe2O4 / C / M' compound and a preparation method thereof using aniline small organic molecules as a carbon source is characterized in that magnetic nano particles of MFe2O4 are in the center, the middle layer is a carbon layer produced by carbonization of the aniline small organic molecules, a thickness of the middle layer is 1-50 nanometers, the outer layer is M' precious metal, and a thickness of the outer layer is 1-100 nanometers. Preparation processes include the following steps: the first step: preparing the magnetic nanometer particles; the second step: preparing magnetic MFeO4 / C compound nanometer materials; the third step: preparing magnetic precious metal shell MFe2O4 / C / M' compound nanometer particle materials, wherein M in the MFe2O4 is Ferrum (Fe), Cobalt (Co), Manganese (Mn), Nickel (Ni), Zinc (Zn), and Copper (Cu) element, or combination of two above elements; and the precious metal M' is Gold (Au), Platinum (Pt), Copper (Cu), and Palladium (Pd) metal or combination of two above metals. Through coverage of the carbon (C) layer, the surfaces of the magnetic nanometer particles carry amidogen perssads so as to be beneficial for further conduct decoration of metal nanometer particles. And surface area of the compound materials is enlarged so as to be beneficial for absorption of organic molecules. The materials have potential application value in environmental, biomedicine and catalysis aspects.