The nano Co0.5Zn0.5Fe2O4 powder was synthesized by hydrothermal method. The effects of the process conditions(crystallization time, crystallization temperature) on the phase, morphology and absorbing properties of Co0.5Zn0.5Fe2O4 were studied by X-ray diffraction(XRD), Transmission electron microscope (TEM) and Vector network analyzer(VNA). The results suggest that pure-phase nano Co0.5Zn0.5Fe2O4 with spinel structure is prepared when the crystallization time is 8 h and the crystallization temperature is 180 ℃. The morphology of the sample is spherical with an average particle size of 10-15 nm. In the 1-18 GHz, the reflectivity of the sample at 16.47 GHz reaches -33.9 dB, and the absorption performance is the best.