Abstract: The research was carried out with the assistance of methods of process mineralogy, in order to figure out the oxidation behavior and occurrence states of vanadium and the effect on leaching recovery of vanadium in oxidizing roasting process of vanadium-bearing limonite(limonite-V) which is the typical vanadium minerals in graphite vanadium ore, as a result, the mechanism of vanadium extraction is discussed. Based on the results, the limonite has transformed into hematite at about 500 ℃, resulting in the changes of vanadium states in roasting process. At the range of 600 to 850 ℃, the vanadium begins to concentrate in areas rich in Al and Si, which makes it possible to achieve higher vanadium recovery; when above 850 ℃, the association between mineral grains and the differential concentration of vanadium can be discovered, which has very vicious effects on vanadium leaching.