Z-type hexaferrite (Ba3(Co0.4Zn0.6)2Fe23.4O41) withBST(Ba 0.5Sr0.5TiO3) additive was prepared by conventional solidstate reaction method. We have investigated the effects of BST additive on the complex permeability, permittivity and microwave absorption in the range of 1 MHz-1 GHz. The results from XRD and SEM indicate that as the amount of BST increases, the major phase changes to Z-phase, simultaneously M-phase and perovskite phase appear, and grain size increases. When the weight percent of BST additive in Z-type hexaferrite varied from 0% to 1.5%, the BST additive not only improved complex permeability and complex permittivity, but also provided broadband reflectivity characteristics. Meanwhile the minimum reflection point shifts to lower frequency with increase of BST content.