Abstract: The process of extracting vanadium from molten vanadium slag was simulated. After vanadium slag was heated to the molten state,CaO was charged and oxygen was blown into the slag,by which vanadium in the slag was oxidized into quadrivalent or pentavalent state and calcium vanadate was obtained.Then acid leaching was employed to extract vanadium. The influence of calcium to vanadium ratio,sulfuric acid concentration and solid-liquid ratio on leaching ratio was investigated. The experiment results show that the calcium vanadate is mainly CaV₂O₅,and with 70% of the slag's particle size smaller than 0.074mm,calcium to vanadium ratio of 0.5~0.9,leaching temperature of 90℃,reaction time of 120min,solid to liquid ratio of 1:5,and sulphuric acid concentration of 20%,vanadium leaching ratio can reach 88% or above.