Carbonyl iron powder was taken as electromagnetic wave absorbent, then the epoxy/ ethyl cellulose microcapsule incorporated with carbonyl iron particles was prepared by means of solvent evaporation. The wave-absorbing property, particle size distribution, characteristics of particle and chemical structure of the microcapsules were characterized by means of vector network analyzer, laser particle size analyzer, ESEM-EDS and FTIR. The result shows that the wall material of the microcapsules consists of carbonyl iron powder and ethyl cellulose, thus the wave-absorption properties of microcapsules incorporated with carbonyl iron powder were reinforced. The smaller carbonyl iron powder has a larger interaction area with electromagnetic waves, therefore, the microcapsules incorporated with smaller particle carbonyl iron particles will exhibit better wave-absorption properties. At 18 GHz, the reflection loss of microcapsules without carbonyl iron particles was -1.63 dB, but the reflection loss of the microcapsules incorporated with 50% carbonyl iron particles can reach -5.08 dB and -5.44 dB for the particle size of 3 μm and 0.5 μm respectively, correspondingly, which are 3.45 dB and 3.81 dB lower than that for microcapsule without carbonyl iron particles, besides, the microcapsules incorporated with 50% carbonyl iron particles of 0.5 μm show excellent dispersibility as well.