W-type barium ferrite (BaZn2Fe16O27)/Antimony-doped tin oxide (ATO) composite materials were synthesized by co-precipitation method, using BaZn2Fe16O27 prepared by traditional solid method and SnCl4·5H2O , SbCl3 as main raw materials.The structure and morphology of the composites were characterized using X-ray diffraction, scanning electron microscopy (SEM), the result showed that BaZn2Fe16O27/ ATO composites were obtained by co-precipitation method, ATO nano-particles were coated on the surface of BaZn2Fe16O27 ferrite.The complex permittivity and complex permeability of BaZn2Fe16O27/ATO composite materials at the frequency range from 2 to 18 GHz were analyzed by vector network analyzer.The strong dielectric property of ATO and the superior magnetic performance of ferrite function coordinately.The result showed that the complex permittivities and dielectric loses of the BaZn2Fe16O27/ATO composites were higher than the single ferrite, when the complex permeabilities and magnetic loses were essentially constant; When the mole ratio of BaZn2Fe16O27/ATO was 1:2, the dielectric constant and dielectric loses reached the maximum, 5 and 0.12.The electromagnetic properties of ferrite/ATO composites obtains a great enhancement because of the synergistic effect of the two-stage absorption.