This paper presents for the first time a successful synthesis of quaternary nanocomposites consisting of graphene, Fe3O4@Fe core/shell nanopariticles, and ZnO nanoparticles. Transmission electron microscopy measurements show that the diameter of the Fe3O4@Fe core/shell nanoparitcles is about 18 nm, the Fe3O4 shell’s thickness is about 5 nm, and the diameter of ZnO nanoparticles is in range of 2–10 nm. The measured electromagnetic parameters show that the absorption bandwidth with reflection loss less than −20 dB is up to 7.3 GHz, and in the band range more than 99% of electromagnetic wave energy is attenuated. Moreover, the addition amount of the nanocomposites in the matrix is only 20 wt %. Therefore, the excellent electromagnetic absorption properties with lightweight and wide absorption frequency band are realized by the nanocomposites.Keywords: electromagnetic absorption; Fe; Fe3O4; graphene; quaternary nanocomposites; ZnO;