Abstract: To solve problems arising during calcified roasting and acid leaching processes in vanadium extraction industrial test,the influence of key process parameters on extraction of vanadium was studied by taking vanadium slag from Pangang as raw materials.The research focused on the influence of Cao/V₂O₅ ratio,roasted materials' particle sizes,metallic iron content in roasted materials and final pH value of leaching slurry on vanadium leaching rate and the influence of oxidizability of roasting atmosphere on the optimum roasting temperature,and the influence of P concentration of leaching liquid on precipitation of vanadium.The results show that a higher vanadium leaching rate can be obtained with CaO/V₂O₅ ratio of 0.54~0.70,the roasted materials' particle sizes of -0.096 mm,metallic iron content in roasted materials equal to or less than 2% and the final pH value of leaching slurry not higher than 4.1.With 15% of oxygen in inlet gas(the corresponding oxygen content in exhaust gas is about 12.5%),the optimum roasting temperature is 850~870℃,and the corresponding vanadium leaching rate is 88.29%~88.66%.When the acid leaching liquid contains 32 g/L of TV,P concentration should be controlled below 0.06 g/L.