Recently, a wide range of studies has been carried out on microwave absorber composites for use in telecommunications, electromagnetic pollution, stealth technology, and other applications. In this study, the microwave absorption properties of polyvinyl butyral (PVB)/polyaniline (PAM) coated-Fe3O4 (COM1) and PVB/Fe3O4 (COM2) nanocomposites with single and double layer were investigated in the 1-14 GHz for different thickness (t(m)) of composites. XRD, FT-IR, TEM, and SEM were used to determine the structure properties of the composites. The Coaxial transmission line method was used to obtain permittivity (epsilon', epsilon '') and permeability (mu', mu '')parameters of the composites. The reflection loss of the single and multilayers of different thicknesses was calculated. It was figured out that the higher value of reflection loss (R-L) (-51.5 dB at 11.9 GHz) was obtained with COM2 composite. However, using PANI has provided a wider absorption range in COM1 composites. It was found that multilayer composites (COM4) provide broadband absorption compared to COM2 and double-layer design (COM3).