Interaction between Ba 2 Ti 9 O 2 0 microwave dielectric ceramics and BaBSiO glass materials was systematically investigated. BaTi(BO 3 ) 2 intermediate phase was induced and its proportion increased with firing temperature. Fortunately, the formed BaTi(BO 3 ) 2 phase does not result in marked degradation on the microwave dielectric properties of the Ba 2 Ti 9 O 2 0 -BaBSiO composite materials. Good microwave dielectric properties (K=13.2, QxF=1150) were obtained by firing the Ba 2 Ti 9 O 2 0 -BaBSiO (50:50 vol.%) materials at 900 o C for 30 min. Precoating a thin layer of BaTi(BO 3 ) 2 materials on the Ba 2 Ti 9 O 2 0 powders prior to processing of the ceramic tapes can markedly suppress the interaction between the Ba 2 Ti 9 O 2 0 and BaBSiO glass, significantly improving the consistency of the microwave dielectric properties for the low temperature cofirable ceramic (LTCC) materials.