Crystallization behaviors of new developed CaO–Al₂O₃ based mould fluxes with TiO₂ addition for casting of high-Al steels were investigated by using DTA techniques combined with SEM-EDS and XRD analysis. XRD and SEM analyzed on the crystallized samples showed that the sequence of crystal precipitation for TiO₂-free mould flux during cooling was MgO, and followed by Ca₁₂Al₁₄O₃₃ during cooling. The sequence of crystal formation for TiO₂-bearing mould fluxes during cooling is CaTiO₃ to MgO, and then Ca₁₂Al₁₄O₃₃. Continuous cooling transformation diagrams (CCT) were constructed for analysis of the crystallization behaviors. The Undercooling values for onset crystallization of various crystals were calculated by using liquidus temperature obtained by heating DTA and crystallization temperature of various crystals. The crystallization temperatures of CaO–Al₂O₃ based mould fluxes increased with increasing TiO₂ content. The undercooling values for onset crystallization of CaTiO₃ decreased with increasing TiO₂ content, which indicating that the crystallization of CaTiO₃ was enhanced with increasing TiO₂ content. The undercooling values for onset crystallizations of Ca₁₂Al₁₄O₃₃ and MgO only changed slightly with increasing TiO₂. This indicated that crystallizations of Ca₁₂Al₁₄O₃₃ and MgO crystals were only slightly influenced by TiO₂ addition. The overall crystallization of mould fluxes was enhanced with increasing TiO₂ content.