Abstract: Gd doped Co₂Z type hexagonal ferrite 3（Ba_0.5Sr_0.5O）·2CoO·0.05Gd₂O₃·10.8Fe₂O₃ was prepared by the conventional ceramic method. The microstructures and high frequency properties of the material were investigated. The results show that the Co₂Z ferrite doped with a small amount of Gd is also the single phase of Co₂Z planar hexagonal structure. The addition of Gd in Co₂Z ferrite can increase the real part μ’ of complex permeability significantly. The Gd doped Co₂Z ferrite exhibits excellent high frequency properties such as high initial permeability up to 13 and high cut-off frequency above 1GHz. With increasing sintering temperature,the real part μ’ of complex permeability increases and cut-off frequency goes down. The addition of Gd has no obvious effect on the complex dielectric constant of Co₂Z ferrite,but the ferroelectric resonance peak of Gd doped ferrite shifts to higher frequency region as a consequence.