The rational design of the aerogel pore structure facilitates the maximum excitation of the materials physicochemical properties, which enables the modulation of their electromagnetic performance. However, the controllable adjustment of the aerogel pore structure remains a significant challenge. Here, the freeze-thawing process and thermal annealing treatment are introduced to prepare reduced graphene oxide (rGO)/iron (Fe)/carbon nanocoil (CNC) aerogels. The composite aerogels with tunable pore structure are obtained by adjusting the content of CNC. Both experiments and simulations confirm that the pore structure with the addition of CNC presents a continuous 3D conductive network, which improves the conductivity loss and polarization loss. Meanwhile, the amorphous carbon structure within the CNC causes structural defects, which further enhance the polarization loss. Therefore, the rGO/Fe/CNC aerogel with optimized pore structure has lightweight and efficient electromagnetic wave absorption. At an ultra-low filling ratio of 0.8 wt%, the effective absorption bandwidth reaches 7.9 GHz and the optimal reflection loss is -43.5 dB. In addition, due to the 3D continuous network interwoven of aerogels and the temperature stability of carbon nanomaterials, composite aerogels have excellent thermal insulation, antifreeze performance, and hydrophobicity. This multifunctional absorber has great potential for application in complex and changing electromagnetic environments.