Abstract: A series of spinel MnZn ferrites were prepared by chemical co-precipitation process,sintered in air,and cooled in vacuum.The effect of ZnO content and sintering process on the properties of the samples was discussed.With the increase of ZnO content,the initial permeability μ_i is greatly enhanced while the saturation magnetization B_S and the Curie temperature T_c falls down.It is found that higher saturation magnetization B_s and initial permeability μ_i can be achieved simultaneously when the sintering temperature is about 1400℃;The sample of ZnO=24.5mol% has the value of μ_i=7041,B_S=310.9mT,H_C=4.3A/m.