In this paper, The optimum oxidation conditions for the formation of Cu-Zn ferrite were investigated using precipitates obtained by the mixture of $CuCl_2{\cdot}2H_2O$, $ ZnCl_2$, $FeCl_3{\cdot}6H_2O$ and NaOH. The precipitates were prepared by coprecipitation method on various temperatures and oxidation conditions. The oxidation products were examined by SEM, XRD, and VSM. The particles obtained at 70($^{\circ}C$) were more spherical and fine than that of prepared at 25($^{\circ}C$), 50($^{\circ}C$), 60($^{\circ}C$), respectively. By $H_2O_2$ oxidation, the saturation magnetization of the powders was little influenced, But, by air oxidation the saturation magnetization of the powders was influenced intricately. According to our experimental data, the saturation magnetization of the powders increased with reaction time and was saturated at 9 hours.