In this study, it is reported for the first time that porous Sm-doped CaFe0.5Mn0.5O3-δ (CFMO) has good microwave absorption properties. In this paper, SmxCa1−xFe0.5Mn0.5O3-δ (x = 0,0.05, 0.1, 0.15, 0.2) (Sm-CFMO) sample powders were prepared by the sol-gel method after calcination at 750 °C. Sm-CFMO was characterized using XRD, SEM, TEM, XPS and VSM, and mixed with paraffin wax for VNA testing. The addition of Sm elements increased the porous structure of CFMO, increased interfacial polarization and defect polarization, and increased oxygen vacancy content, resulting in enhanced charge polarization and dipole polarization, while greatly optimizing the impedance matching of CFMO, and the compounding with paraffin wax also increased the composite with paraffin also increases the interfacial polarization capacity of the material, thus improving the microwave absorption performance of the sample. Moreover, as a new type of absorbing material, this material has great potential for development in the field of absorbing materials and provides a new direction for the development of absorbing materials in the future.