Ferrite and carbonyl iron power are the major absorbing components of conventional radar absorbing materials (RAM). However, conventional RAM made of the aforementioned single-absorbing components cannot meet the comprehensive requirements of “thin, wide, light, and strong.” By analyzing the complementary relationship among ferrite and carbonyl iron power, a carbonyl iron coated core-shell nano composite absorbent system is established. In addition, by changing the deposition temperature to adjust the morphologies and absorbing properties of powders, excellent performance of the new core-shell structure absorbent is obtained. The nano carbonyl iron (CI) shell in situ grown on Ni_0.4Zn_0.2Mn_0.4Ce_0.06Fe_1.94O₄ (NZMCF) surface by metal organic chemical vapor deposition (MOCVD) for using as electromagnetic wave (EMW) absorbing materials. X-ray diffraction, scanning electron microscope and energy dispersive spectrometer analyses show that NZMCF-CI composites successfully prepared with a core-shell structure. Optimizing the weight ratio of CI would likely cause the composites to attain the EM parameters necessary in EMW absorbing materials, a minimum reflection loss (RL) was -39.9 dB to the corresponding thickness was 1.8mm, and the RL exceeds -10 dB from 3.8 to 18.0 GHz. The RL exceeds -20 dB from 3.2 to 18 GHz and -10 dB from 2.5 to 18 GHz for the absorber thickness from 0.8 to 2.6 mm, which covers almost the whole 2 to 18.0 GHz.