Using starting BaTiO3 powders of various particle sizes, we investigated the densification and dielectric characteristics of BaTiO3 ceramics sintered at low temperature with the addition of ZnO-B2O3-SiO2 (ZBS) glass as sintering aids. Scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and LCR meter were used to examine the structure and dielectric properties. The results indicated that the particle size of raw powders had a dramatic influence on the densification and dielectric properties of BaTiO3 ceramics. The grain size of the final ceramics was almost proportional to the particle size of the starting BaTiO3 powder. Moreover, the tetragonality (c/a ratio) and Curie temperature is increased with the increase of grain size of the BaTiO3 ceramics. The relative density of 96% and the dielectric constant of 1440 were obtained for the BaTiO3 ceramics prepared with the raw powders of average particle size of 800 nm. In addition, the sintering temperature was reduced to 1100 °C due to the addition of 5 wt% ZBS glass.