The factors that influence the complex permeability of the epoxy-ferrite composite were investigated, and the frequency dispersion behavior model for the complex permeability was proposed. The complex permeability of the composite was measured by an impedance/gain phase analyzer and a network analyzer in the frequency range from 1 MHz to 5 GHz. The permeability of the composite was increased with increasing particle size. The frequency dispersion behavior was found to be dependent on the porosity of the composite at a given particle size and ferrite content. The relaxation curve of the complex permeability became broader and flatter as the porosity increased. The equation proposed in this article coincided with the frequency dispersion behavior of the complex permeability of the composite fairly well. It was also found that the variation of sigma and nu had a close relationship with the shape variation of the frequency dispersion curve, and that sigma and nu were the parameters related to the porosity, particle size, and particle size distribution.