Abstract: Iron coated carbon nanotube (CNT) nanocomposite absorbents were prepared by a metal organic chemical vapor deposition method using carbonyl iron as the Fe precursor. The microstructures and electromagnetic properties of the composites were characterized by XRD, FESEM, TEM, and a vector network analyzer. Results show that the morphology and microwave absorption properties of these core-shell composites are controlled by changing the deposition temperature. The number of iron nanoparticles deposited on the surface of the CNTs gradually increases with increasing deposition temperature in the range 210-240℃. Too high a temperature (270℃) causes agglomeration of the Fe nanoparticles on the surface of the CNTs. When the thickness of the electromagnetic coating is 2.9 mm, the composite prepared at 240℃ has the best microwave absorption, with a maximum absorption bandwidth of 6.1 GHz (10.2-16.3 GHz), a minimum reflectivity of -28.3 dB and an absorption intensity less than -10 dB at 6.1 GHz.