Abstract: Magnetic iron particle-doped expanded graphite was prepared by dipping, stirring and standing an expandable graphite for 5-8h in ferrocene then expanding at 500℃. The surface morphology and composition of the expanded graphite were characterized by SEM and elemental analysis while the magnetization curves, magnetic susceptibility and the attenuation properties for an 8mm wavelength electromagnetic signal were characterized by a vibration magnetometer. Results showed that ferric oxide was deposited on the surface of the expanded graphite. The average magnetic intensity of the expanded graphite prepared is higher than 8emu/g under a magnetic field intensity of 0-7.958×105A/m. The largest attenuation is over-10dB and its mass extinction coefficient is over 1.0g/m2 in the wave length of military radar, which is better than a current millimeter wave radar shielding material.