Glasses with composition 50Bi 2O 3–(50 − x) B 2O 3– xGeO 2 ( x = 0, 5, 10, 15 mol%) were prepared by conventional melting method. The thermal properties were investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of GeO 2. The glass transition temperature ( T g), onset crystallization temperature ( T x) and Δ T ( T x − T g) increase as well. The cut-off edges in ultraviolet and infrared shift to longer wavelength by the addition of GeO 2. Infrared, Raman and XPS results indicate that the glass network consists of [Bi–O 6] octahedron, [BO 3] triangle, [BO 4] tetrahedron and [GeO 4] tetrahedron and borate oxide mainly exists in [BO 3] units. XPS result indicates Ge 4+ ions form steady [GeO 4] tetrahedra units in the glass network and the number of non-bridging oxygens decreases with the addition of GeO 2.