The chemical composition of the refining slag is mainly Al2O3 >55.0%, CaO 5.0-20.0%, SiO2 <1.5%, MgO 5.0-20.0%, S <0.10%, P <0.05%. Its function is to form a calcium aluminate slag system during the molten steel refining process, thereby achieving the purpose of adsorbing inclusions and purifying steel quality, while enhancing the desulfurization efficiency of the slag and further reducing costs. This product has advantages such as rapid slag formation, low melting point, excellent desulfurization capability, environmental friendliness, and material savings. It is suitable for refining the majority of steel grades, such as automotive sheet steel, aluminum-killed steels, high-carbon steel, medium-carbon steel, and gear steel.