To improve the synergistic effect between dielectric and magnetic loss is a practical and effective way in optimizing electromagnetic wave absorbing materials. The composites of metal particles and carbon ligands derived from metal organic frameworks have gained wide attention. In this study, Co particles and multiwalled carbon nanotubes (CNT) were successfully synthesized covering the surface of silicon carbide (SiC) fibers, and the morphology, interfaces and electromagnetic wave absorption performance were explored. For sample SiC@Co/CNT, the minimum reflection loss value can reach –70.22 dB at 11.21 GHz with the thickness of 2.12 mm. The effective absorbing bandwidth can reach up to 6.03 GHz with the thickness of 1.71 mm, which covers the entire Ku band. It brings more interfaces between Co particles and CNTs as well as SiC fibers and Co/C nanosheets. The interfacial polarization has been hugely enhanced, and the microwave absorbing properties have been improved. This article reports on the impedance matching of magnetic and non-magnetic components and the heterointerface engineering, which can be effective strategy and inspiration to illustrate the relationship between components, structures and functions of electromagnetic wave absorbing materials.