Ba1−x−ySryCaxTiO3 (BSCT, y=0, x=0–1; y=0.05, x=0–0.95; y=0.1, x=0–0.9; y=0.13, x=0–0.87; and y=0–0.20, x=0.5−y/2) ceramics were prepared using the solid-state reaction method in this paper. Their structural and dielectric properties were characterized. The results of refined X-ray diffractometer analysis showed that in the Ba-rich area, the solubility limits of Ba1−xCaxTiO3, Ba0.95−xSr0.05CaxTiO3, Ba0.90−xSr0.10CaxTiO3, and Ba0.87−xSr0.13CaxTiO3 lay around x=0.24, x=0.30, x=0.34, and x=0.36, respectively. In the Ca-rich area, the solubility limits of Ba1−xCaxTiO3, Ba0.95−xSr0.05CaxTiO3, and Ba0.90−xSr0.10CaxTiO3 lay around x=0.92, x=0.84, and x=0.70, respectively. The dielectric constant and the tunability decreased with Ca addition, except for the solubility limit areas, near which the dielectric constant and tunability increased drastically. For the BSCT series ceramics with a 15–20 mol% Sr content, the electrostrictive strain of the samples was still around 0.15%.