The electromagnetic interference is prevented by the high magnetic loss of the ferrite. The absorbing property of electromagnetic wave could be improved by the ferrite that has a finer and more uniform microstructure. The thermal decomposition of organic acid salt provided the uniform composition and fine powder. The absorbing properties of electromagnetic wave were evaluated by the relative complex permeability, permittivity, and the attenuation which is calculated from the results of network analyzer. The permeability and permittivity were increased with increase of the density and with decrease of the grain size. The matching thickness could be reduced with increasing sintered temperature. The attenuation of the Cu-Ni-Zn ferrite showed over 20dB when the matching thickness and the matching frequency range were 6.75mm and from 160MHz to 640MHz, respectively.