Abstract: BaSrZnSi₂O₇-Ba_0.5Sr_0.5TiO₃ composite ceramics were systematically characterized in terms of phase composition, microstructure and dielectric properties. It is found that dielectric permittivity peaks of the samples shifted to low temperatures initially and then kept invariable with increasing BaSrZnSi₂O₇content. Tunability showed a similar trend to Curie temperature. The variety in Q value is mainly related to whether the ‘doping’ effect or ‘composite’ effect is dominated. The sample with 60wt% of BaSrZnSi₂O₇ possess a high tunability of 16%(10 kHz), a low dielectric permittivity of 152 and a high Q value of 417 (2.720 GHz), making it a promising candidate for applications as electrically tunable microwave devices.