Abstract: Composite of nanosized α-Fe and barium-W (Ba-W) hexaferrite phase has been synthesized by the ceramic processing rout. Pure Ba-W hexaferrite (Ba(Zn0.7Co0.3)2Fe16O27) was firstly prepared by calcinations. At different temperature, partly, the hexaferriet phase changed into FeCo metallic phase and BaFe2O4. These conclusions are based on the results of X-ray diffraction. The study of magnetic properties at microwave frequency shows that the permeability spectra changes from the type of ferromagnetic resonance into the type relaxation. The loss mechanism changes obviously.