The nanocrystalline Co0.7Cu0.1Zn0.2Fe2O4 ferrites and the polypyrrol (PPy) -Co0.7Cu0.1Zn0.2Fe2O4 nanocomposites were prepared by self-propagating combustion method and an in situ polymerization method, respectively. The structure and morphology of the synthesized materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectrometry (FTIR), and the dielectric, microwave absorbing and magnetic capability of the two materials were studied by wave-guide method and vibrating sample magnetometer (VSM), respectively. The results show that the pure spinet Co0.7Cu0.1Zn0.2Fe2O4 ferrites are obtained and a small amount Co2+ ions of the octahedron ferrites are replaced by Cu2+ ions, which results in the reduce of lattice constant of the Co0.7Cu0.1Zn0.2Fe2O4 ferrites. The two powders both have good dispersity and the average size of the two kinds of particles is about 15 nm and 50 nm, respectively. In the measuring frequency range of 5.0 similar to 20.0 GHz, the reflection loss of PPy-Co0.7Cu0.1Zn0.2Fe2O4 composites is between -16.25 and -20.27 dB, and the reflection loss maximum value is about -20.27 dB at 18.0 GHz with a bandwidth of 2.0 GHz (full frequency width at about a half of the peak response), which is obviously higher than that of the Co0.7Cu0.1Zn0.2Fe2O4 ferrites. The saturation magnetization (M-s) and remanent magnetization (M-r) of the PPy-Co0.7Cu0.1Zn0.2Fe2O4 composites are 1.29 emu/g and 0.429 emu/g, respectively, which are smaller than those of the Co0.7Cu0.1Zn0.2Fe2O4 ferrite. But the coercive force (H-o) of the PPy-Co0.7Cu0.1Zn0.2Fe2O4 composites, which is 38.96 KA/m, is greater than that of the Co0.7Cu0.1Zn0.2Fe2O4 ferrite.