The room-temperature furnace slag from a pig iron plant was investigated and the corresponding chemical composition was obtained. The temperature dependences of viscosity coefficient, resistance, and heat transfer coefficient were measured in detail. With increasing temperatures, the value of viscosity coefficient and resistance is lowered, while that of heat transfer coefficient enlarged. The fit of temperature dependence of viscosity coefficient gives y0=1.9672, A=1.95×1019, t=31.8. Above 1000 oC, solid slags become melted and flown, with abrupt increase of heat transfer coefficient. Based on the designing of medium-frequency induction furnace, we can conclude as follows: (1) the liquid slags are conductive with a small conductance, which reveals that the medium-frequency induction furnace can be employed with a small power; (2) heat transfer coefficient gets enlarged with increasing temperature, which indicates that the higher the temperature is, the larger the heat loss gets.