Abstract: In order to achieve the effective extraction for the vanadium from a low-grade vanadium ore,low-temperature sulphated roasting pretreatment technology was adopted for strengthening crystal structure destroying and phase transformation of vanadium-bearing mineral illite during roasting process,which created favorable conditions for the extraction of vanadium from calcine during water leaching. The influence of roasting temperature,roasting time,particle size of raw ore and sulfuric acid dosage on vanadium leaching rate and phase evolution during roasting were investigated. The results showed that the vanadium leaching rate could reach 83. 64% under the optimal roasting conditions of the roasting temperature of 250 ℃ for 2 h, -0. 096 mm of raw ore and 40% sulfuric acid dosage. XRD analysis of the raw ore,roasted products and leached slag showed that under the synergistic effect of sulfuric acid and temperature rising,the aluminosilicate mineral lattice in the raw ore is effectively destroyed,the illite reacts with sulfuric acid to form misenite and easily leached munirite,and the gangue mineral calcite is transformed into gypsum in the roasting process,which creates favorable conditions for the extraction of vanadium by water leaching. The thermodynamic calculation of roasting process further verified the feasibility of low temperature sulfated roasting and water leaching process for vanadium extraction.