The organic-inorganic ErFeO3/polyaniline (ErFeO3/PA) composites were synthesized by combining sol-gel self-propagating combustion method and in-situ oxidative polymerization method. The microstructure, FTIR spectra, surface area and pore volume, magnetic properties and electromagnetic parameters of the synthesized samples were studied in detail. The reflection loss of obtained products in the frequency range of 1–18 GHz was calculated. In addition, the effects of different concentrations of ErFeO3/PA on microwave-absorption properties were studied. The sample of 30 wt% ErFeO3/PA in paraffin matrices had good absorption properties. When the given thickness was 2.0 mm, the reflection loss (RL) lower than −10 dB was in the 12.1–16.3 GHz range, covering almost two-thirds of the Ku band (12–18 GHz), and the maximum RL reached − 39.0 dB. The combination of ErFeO3 and PA generated plenty of heterogeneous interfaces and induced the multipolarization process in heterogeneous interfaces, resulting to the excellent microwave-absorbing properties.