Sintering and dielectric characteristics of substrates were estimated by mixing rate of alumina and potashborosilicate glass(PBSG) powders. PBSG powders were used 7761(corning code)and alumina powders were used in extra pure rate(99.9%) and had 0.1 ${mu}$m mean size. After ball milling with organic additives green sheets which were casted by doctor blade machine were sintered at 800$^{circ}C$ for 1∼3hrs. Microstructure, linear shrinkage and dielectric constant of substrates were surveyed in order to fabricate low-dielectric and low tem-perature sintering substrate.