<p>Ba₂Co₂Fe₁₂O₂₂ (Co₂Y, 1wt.%, 2wt.%, 3wt.%, and 4wt.%) added Ni_0.8Zn_0.2Fe₂O₄ polycrystalline ferrites are prepared by solid-state reaction method. The composite materials’ crystal structure, micromorphology, and magnetic properties were systematically characterized using an X-ray diffractometer, scanning electron microscope, energy-dispersive spectrometer, and vibrating sample magnetometer. The experimental results showed that the addition of Co₂Y had a minimal impact on the main crystal phase structure of the Ni_0.8Zn_0.2Fe₂O₄ ferrite but caused changes in the lattice constants and adjustments in grain size, leading to a more uniform and compact granular structure. With the increase of Co₂Y, the saturation magnetization of the composite materials slightly increased, while magnetic loss exhibited a decrease followed by an increase. The results indicated that the addition of Co₂Y could effectively optimize the magnetic properties of Ni_0.8Zn_0.2Fe₂O₄, enhancing its potential application in high-frequency low-loss magnetic devices.</p>