Abstract: Mg_0.5Co_0.5Fe₂O₄/graphite composites of different mass ratios were prepared by hydrothermal method. The composition, morphology, magnetic properties and electromagnetic properties of the composites were analyzed with X-ray diffractionmeter(XRD), scanning electron microscope(SEM), vibrating sample magnetometer (VSM) and network analyzer. The results show that part of Mg_0.5Co_0.5Fe₂O₄ particles are enchased between graphite layers, others are covered on the surface of graphite layers; the saturation magnetization of Mg_0.5Co_0.5Fe₂O₄/graphite composites decreases with the increase of graphite content; the imaginary part of permittivity of Mg_0.5Co_0.5Fe₂O₄/graphite composites is greater than that of Mg_0.5Co_0.5Fe₂O₄; the reflection loss of Mg_0.5Co_0.5Fe₂O₄/graphite composites is below-15 dB at the frequency range of 15.5-17.0 GHz, and the reflection loss peak reaches -31 dB.