Crystallization kinetics and the structure of mold fluxes with SiO2 being substituted by 0, 5, and 10 pct TiO2 were studied by differential thermal analysis technique and Raman spectroscopy, respectively, to explore the effect of TiO2 on the crystallization behavior of the slag. Crystallization kinetics analysis shows that the activation energy for crystal growth increases with the increase of TiO2 substitution, implying that TiO2 substitution for SiO2 in mold fluxes produces negative effects on crystal growth and retards the crystallization process. Raman spectral study indicates that TiO2 enters the system mainly in the form of [TiO4] in monomer structure unit, and simultaneously, there appear relatively small amounts of [TiO6] structure unit. The introduction of TiO2 leads to a decrease of the dimer and chain Si-O-Si structure unit (Q1 and Q2).