Photolithographic process is one of the eco-friendly processes for forming the pattern of the barrier ribs in PDP. Controlling the refractive index of glass is important to develop a photosensitive paste for photolithographic process. We studied the refractive index and the structural transition of these glasses by measuring the refractive index, reflectance, density and dielectric constant with changing the SiO2/B2O3 ratio in the SiO2-B2O3-Al2O3 glass system. The refractive index was investigated to the relationship between the thermal and optical properties depending on the composition. It suggests that the thermal and optical properties in borosilicate glasses should be correlated to the glass structure with the SiO2/B2O3 ratio.