The conversion and dissolution mechanism of vanadium in the process of blank roasting and alkali leaching were studied. The results showed that vanadium in spinel (FeV2O4) was gradually oxidized into VO2 and V2O5, and then formed vanadate by combining with Ca/Mn/Mg. Leaching process ccan be divided into low temperature leaching (T<180℃) and high temperature leaching. Low temperature leaching only extracted vanadate and vanadium oxide, while high temperature leaching (T≥180℃) extracted the vanadium in the form of solid solution in calcium silicate. Vanadium leaching rate in blank roasting and alkali leaching process reached 97.63%, while the rate of traditional process was only 80%. The application of blank roasting and alkali leaching process could realize the high efficiency and clean extraction of vanadium from vanadium-bearing slag.