Dy3+doped Mn-Zn ferrites Mn0.3Zn0.7Fe2-xDyxO4(x=0,0.01,0.02,0.03,0.04)were prepared by the conventional solid-state reaction.The crystal structure,surface morphology and electromagnetic properties of the calcined samples were characterized by X-ray diffraction analysis(XRD),scanning electron microscopy(SEM)and network analyzer(Agilent 8722ET).All the XRD patterns showed the single phase of the spinel-type ferrite without other intermediate when x≤0.03.The average crystallite size was about 44-56 nm.The microwave electromagnetic properties of the samples were studied at the frequency range from 2 GHz to 18 GHz.It was shown that small amounts of Dy3+substitution could adjust microwave electromagnetic parameters magically.The tan δ exhibited a maximal peak when x=0.03,and the peak value was 0.56.It indicated that the microwave electromagnetic loss properties were excellent when x=0.03.Furthermore,the reasons were also discussed using electromagnetic theory.The reflection loss(RL)increased with the Dy3+content when x≤0.04.The Mn0.3Zn0.7Fe1.97Dy0.03O4 ferrite displayed excellent microwave absorption properties.The frequency(with respect to-10 dB)started from 11.9 GHz,and the bandwidth reached about 3.5 GHz.The peak value of RL was about-20.5 dB at a matching thickness of 2.7 mm.