Abstract: To address the problems of low vanadium utilization rate during vanadium extraction process through vanadium slag roasting,unavailability of chromium and severe environment pollution caused by ’three wastes’,an improved efficient and cleaner technology of vanadium extraction by sub-molten salt method is introduced based on excellent physical or chemical properties of sub-molten salt and design of reaction-separation coupling process.The new sub-molten salt technology can reduce the decomposition temperature of vanadium slag to 200～400 ℃from 850 ℃ with vanadium conversion rate up to over 95% and chromium recovery rate up to over 80%,which are expected to tackle the resource and environmental problems that have bottlenecked the application of traditional vanadium extraction process.