An absorbing medium is prepared using nanosize carbon black (CB) blended with nanosize silicon carbide (SiC). The medium improves the wave absorption properties and the wave band of the single CB absorbent. The microstructure, conductivity, dielectric property, and microwave absorption of the material are studied by means of field emission scanning electron microscopy, trielectrode method, and vector network analyzer respectively. The results show that SiC can reduce the percolation threshold of CB/epoxide resin composite. Addition of certain mass of SiC can improve the microwave absorption of the composite. When 5wt.% carbon black is blended with 50wt.% SiC to fabricate a composite with a 2mm thickness, the maximum reflection loss becomes −41dB at 9GHz, and the −10dB bandwidth reaches 6GHz. Thus, the prepared composite has the potential for use in electromagnetic absorption.