Abstract: Glass forming region and crystallization behavior of TeO₂-B₂O₃-BaO glass were studied by quenching method, differential thermal analysis (DTA), X-ray diffraction (XRD) and Raman spectrum. The results showed that crystals like γ-TeO₂, α-TeO₂, BaTe₄O₉ and BaTe₂O₅ were precipitated in binary system. However, glass forming region for the ternary system is satisfactorily large and devitrification tendency of the glasses in the region has been improved, indicating that the glass might be potential cladding glass of tellurite optical fiber.