BSTO/Mg2Si04/MgO ceramic composites were fabricated by conventional ceramic processing. The microstructures and dielectric properties of the samples were measured and investigated systemically. The effects of the doping of Mg2SiO4/MgO on the microstructures and dielectric properties of BSTO/Mg2Si04/MgO ceramic composites were investigated. The results show that compared with the other BSTO ceramic composites, BSTO/Mg2SiO4/MgO ceramic composites not only can be sintered at a lower temperature but also keep a higher tunability while the dielectric constant decreases. The typical composition of BSTO/39wt/% Mg2SiO4/17wt% MgO has a dielectric constant of ~80.21, a dielectric loss of -0.003 and a tunability of ~12% under applying 2kV/mm dc bias field.