Development and application of fluorine free mould fluxes have been widely studied in recent years. Some research has shown that B₂O₃ and TiO₂ are potential substitutes for F^– in mold fluxes. In this study, Structure of CaO–B₂O₃–SiO₂–TiO₂ glass system has been studied by Raman spectroscopy. The influence of basicities (CaO/SiO₂) and contents of B₂O₃ and TiO₂ on the structure of CaO–B₂O₃–SiO₂–TiO₂ glasses were examined. Experimental results indicate that TiO₂ exists in the system in the form of [TiO₄] as network former in range of 0–15% in mass. The degree of polymerization of this system decreases with increase of basicities. The increase of B₂O₃ leads to more [BO₄] tetrahedral units. It is concluded that both B₂O₃ and TiO₂ behave as network forming oxides within the studied system.