Electromagnetic wave absorbing materials with a microwave absorption capacity over a wide frequency range and a superhydrophobic surface are of great importance for their applications in stealth technology, particularly, in high humidity environments. In this paper, Fe3O4 nanopearl decorated carbon nanotubes stemming from carbons onions (CNOs/CNTs@Fe3O4) have been successfully fabricated using a facile flame strategy, with brass foil as a substrate and catalyst. Fe3O4 nanopearls from the thermal decomposition of iron(iii) acetylacetonate were in situ decorated on carbon nanotubes stemming from the ripening of the self-assembly of carbon onion aggregates from the incomplete combustion of ethanol. Notably, this nanocomposite film exhibited a good microwave absorption performance with a wide absorption frequency over a range of 6-18 GHz based on the cooperation of the dielectric loss of the carbon nanotubes and the magnetic loss of the Fe3O4 nanoparticles. Furthermore, the nanocomposite film displays superhydrophobic properties and a low adhesive force that makes it a good candidate for water shedding stealth materials.