Abstract: With the intensification of electromagnetic pollution, absorbing materials have attracted the attention of researchers, and airgel has the potential to become an ideal absorbing material due to its light weight and porous characteristics. PVA/SiO₂ nanofibers were prepared by electrospinning from polyvinyl alcohol (PVA) and ethyl orthosilicate (TEOS), the flexible SiO₂ nanofibers were homogenized in sodium alginate (SA) solution and freezedried to obtain SA/SiO₂ aerogels. SA/SiO₂/AlBSi and SA/SiO₂/FeCl₃ aerogels were prepared by introducing AlBSi and FeCl₃ as dopants, respectively. Microwave absorbing properties of three kinds of aerogels were analyzed. The results show that there are small particles on the surface of SiO₂ nanofibers, which are the SA/SiO₂ aerogel doped by FeCl₃. This granular structure produces multiple reflection and scattering, interface polarization, which improves the dielectric loss performance of aerogels. After adding FeCl₃, the imaginary part of the magnetic loss of the aerogel increases, which improves the magnetic loss performance of the aerogel. Thus, the overall wave absorption performance of aerogel is improved. When the thickness is 3 mm, its maximum absorption peak is –23.85 dB, reaching 14.42 GHz. It has an effective absorption bandwidth of 1.3 GHz (13.82-15.12 GHz). It is a light material with good wave absorption performance.