Abstract: The composite permeability in the range 1～1000MHz of the conductive and magnetic composite consisting of nickel powder and Ni Zn ferrite was studied. It was found out that, when the nickel content was equal to or less than 47.5%, the composite permeability (μ′,μ″) accorded with the usual composite rules, and that, when equal to or greater than 63.3% and the frequency was in the range 500～1000MHz, an unusual phenomenon appeared, where the real permeability μ′ increased with the frequency increasing, and the imaginary permeability was greater than of the single material in a certain frequency range. This is because the heat from the eddy attenuation of nickel powder in the higher content could change the real and imaginary permeability (μ′,μ″) of Ni Zn ferrite.