Electrical conductivity of molten slag is an important physicochemical property for designing the refining process in elec-tric smelting furnaces. Though conductivities of many slag systems have been measured, the quantitative relationships of conductiv-ity with slag composition and temperature are still very limited. In this article, the Arrhenius law was used to describe the experi-mental data of eonductivities for CaO-MgO-Al_2O_3-SiO_2, CaO-Al_2O_3-SiO_2, CaO-MnO-Al_2O_3-SiO_2, as well as CaO-MgO-MnO-Al_2O_3-SlO_2 systems, and it is found that activation energy can be expressed as a linear function of the content of components, where the optical basicity of slag must be within the range of 0.58 to 0.68.