Abstract: The behavior of Al₂O₃ in titanium slag was discussed by combining the production practice of electric-furnace with the theoretical basis of titanium slag smelting. It is concluded that the relative high Al₂O₃ content in titaniferous iron ore leads to increasing of the viscosity and the melting-point of high titanium slag, irregularity in furnace operation and technical-and-economic indexes depression. Besides, the relative high Al₂O₃ content in titaniferous iron ore also has negative influence on the enriching of TiO₂ and the operation of chloridizing process.