In the low temperature sinterable glass system of BaO–B2O3–SiO2, the structural changes of the glasses and the resultant changes in the properties of the glasses were examined as a function of BaO content. 11B MAS-NMR analysis was conducted in order to examine the coordination number of borons in the glass. It showed that the amount of O4 was greatest at 35 mol% of BaO. The glass transition temperature, hardness, thermal expansion coefficient and dielectric constant of the glasses were examined and the results were explained on the basis of the structural change.