Abstract: BaFe₁₂O₁₉ (BaM)/PANI composites samples were prepared by in-situ polymerization method. The phases, morphologies and structures properties of as-prepared samples were characterized and analyzed by X ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR). The magnetic and electromagnetic properties of as-prepared samples were characterized and analyzed by vibrating sample magnetometer (VSM) and vector network analyzer (VNA). The results show that the characteristic peaks of PANI weaken or even disappear with the increase of BaFe₁₂O₁₉ content, the composite samples have obvious agglomeration phenomenon, the PANI has effect on the locations of vibration absorption peaks of BaFe₁₂O₁₉, the saturation magnetization of as-prepared samples increases with the increase of BaFe₁₂O₁₉ content. The as-prepared sample has the best absorption performance, and the reflection loss reaches -41.44 dB, when the mass ratio of BaFe₁₂O₁₉ and An is 1:1, effective thickness d equals to 6.5 mm, and frequency is about at 17 GHz.