Abstract: To understand inclusions in tire cord steel, the solidification process has been analyzed and the conclusions drawn as follows. Al₂O₃ precipitates earlier during solidification and the growth rate depends on the diffusion of A1 in molten steel; SiO₂ begins to precipitate when the solidification fraction is 0.44, and the growth rate depends on the diffusion of O. The inclusion radius increases with the decrease of cooling rate, the radii of Al₂O₃ and Al₂O₃-SiO₂ inclusions are 2.5 μm and 4.7 μm, respectively, after solidification as the cooling rate is 100 K·min^-1. SiO₂ content increases and Al₂O₃ content decreases during solidification.