In this study, a binary CaO–B 2 O 3 –SiO 2 (CBS) glass composite CBS 950 comprising a high SiO 2 content (67.3mol%) and a low SiO 2 content (23.3%) of CaO–SiO 2 –B 2 O 3 glasses was prepared. The sintering behavior, structural evolution, and dielectric properties of the binary glass composite were characterized and compared to those of a single CBS glass (CBS-11) with the exact same composition. CBS-11 glass densified rapidly within a narrower temperature range (≈800°C) as compared to CBS-950 glass (from ≈700°C to 875°C). It was found that crystallization of CaB 2 O 4 phase in CBS-950 glass was easier than that in CBS-11 glass during heat treatment. Activation energy of CaB 2 O 4 phase in CBS-950 glass was determined to be 307kJ/mol. The best glass-ceramic was resulted from CBS-950 glass sintered at 900°C, which possesses a dielectric constant of 3.77 and a dielectric loss of 0.0012 at frequency of 4.3GHz. CBS-950 glass is superior to CBS-11 glass for use as LTCC substrates in terms of overall performance.