The glass with excellent optical and dielectric properties was prepared by changing the composition of BaO-TiO2-SiO2 ternary system. The results show that with the increase of SiO2 content, TiO2 content decreases, when the mole fraction of BaO was 30%, the thermal expansion coefficient reached the minimum when the mole fraction of SiO2 was 40%, while Tg and Tp first increase and then decrease. The transmissivity of the glass sample in the near ultraviolet region was very small. After the crystallization treatment for 2 h, the proportion of crystals increased first and then decreased, and only Ba2TiSi2O8 crystal phase was precipitated. During the study of the dielectric properties of glass samples, it was found that the dielectric constant gradually decreased with the decrease of TiO2 content, the dielectric loss first decreased and then increased, and the dielectric properties of glass ceramics first increased and then decreased. When the mole fraction of TiO2 was 30%, with the increase of SiO2 content and the decrease of BaO content, the thermal expansion coefficient of the glass gradually decreased, while Tg and Tp gradually increased. With the decrease of BaO content, the content of precipitated crystals gradually decreased, and the dielectric constant and loss of the samples gradually decreased. This study provides a reference for the systematic study of dielectric properties of BaO-TiO2-SiO2 system glass.