Abstract: In this paper the desulfurization ability of CaO-Al₂O₃-SiO₂-TiO₂ slag was studied through the desulfurization experiment by using 10 kg inductive furnace and theoretical calculation by using thermodynamic software Factsage,in order to determine the impact of binary basicity,mass percent of Al₂O₃ and TiO₂ on desulfurization ability. Calculation indicated that binary basicity had a significant effect on suphher distribution coefficient and the effects of other two factors were invisible. Under the experimental conditions,the optimal combination of parameters for gaining the highest sulphur distribution coefficient for the slag were binary basicity of 7,30% Al₂O₃ and 3% TiO₂,the resulting sulphur distribution coefficient was 58.14. While the content of TiO₂ was lower than 3%,the desulfurization ability of CaO-Al₂O₃-SiO₂-TiO₂ slag was similar to CaO-Al₂O₃-SiO₂ slag,and the slag system could meet the desulfurization requirements of steelmaking slag.