<p>Formation and evolution of inclusions in low-aluminum Ti-containing 51CrV4 spring steel under BOF (basic oxygen furnace)–LF (ladle furnace)–CC (continuous casting) process were investigated by industrial trials and thermodynamic calculations. During LF refining, deoxidation products including Al₂O₃, Al₂O₃–Ti₃O₅–SiO₂–MnO and Al₂O₃–SiO₂–MnO are modified as MgO–Al₂O₃, CaO–Al₂O₃–SiO₂, CaO–Al₂O₃–MgO and CaO–Al₂O₃–SiO₂–MgO. When reoxidation during ladle casting is quite serious, inclusions such as Al₂O₃, Al₂O₃–Ti₃O₅–SiO₂–MnO, and Al₂O₃–SiO₂–MnO may regenerate. A handful of Ti carried by alloy into liquid steel has less influence on inclusions during LF refining; Ti-containing inclusions mainly transiently exist as an intermediate product of deoxidation process and then are gradually modified by [Al], [Ca] or [Mg]. Thermodynamic calculation and experimental results reveal that tundish flux is the main source of reoxidation in ladle casting process. Further calculations taking into account of the influence of inclusions before casting indicate that reoxidation within a certain of degree leads to the generation of a large amount of high melting point inclusions including CaO·2MgO·8Al₂O₃, CaO·MgO·7Al₂O₃, MgO·Al₂O₃, CaO·6Al₂O₃ and Al₂O₃ in molten steel, which is basically consistent with experimental results, and more high melting point inclusions will generate as reoxidation becomes severer. On this basis, severer reoxidation will deplete [Si], [Mn], and [Ti] in steel melt, resulting in the formation of liquid inclusions composed of Al₂O₃–Ti₃O₅–SiO₂–MnO(–CaO). These results are of guiding significance for controlling inclusions in Al-killed Ti-containing spring steel.</p>