Abstract: The CaO-SiO₂-B₂O₃ system glass ceramics with high silica glass and SiO₂ were investigated.And the influence of the two different forms of SiO₂ on phase composition,microstructure and dielectric properties was also discussed.The results show that whatever forms of SiO₂ in CSB glass ceramics could decrease the dielectric constant,while high silica glass increase the dielectric loss.The material with 15 wt% SiO₂ could be sintered at 850℃ with the dielectric constant about 6.01 and dielectric loss 1.22×10^-3 at 10MHz.The dielectric constant of the products don’t change with the frequencies from 5 to 10MHz.The major phase of the materials are Quartz,CaSiO₃ and CaB₂O₄.