Abstract: Based on the water quality purification of recharge water in an iron mine，the nanofiltration process of mine water was studied in depth from the aspects of nanofiltration membrane pretreatment requirements，nanofiltration membrane fouling prevention，colloidal pollution prevention，biological pollution prevention，organic pollution prevention and membrane deterioration prevention，and a set of high efficiency and energy saving mine water purification technology with nanofiltration as the core is proposed. The combined water purification technology with nanofiltration as the core，such as 'clarifier flocculation sedi⁃ mentation+multi-media filtration+self-cleaning mechanical filtration+nanofiltration membrane separation technology+sodium hypochlorite disinfection '，was used to treat mine water. The water quality of the produced water meets the national standard of recharge water quality. The operating cost is about 30% lower than that of reverse osmosis technology，and the first metallurgical mine demonstration project in China is built. The research results can provide technical support for the popularization and application of nanofiltration technology in metallurgical mining industry.

Key words: mine water reinjection, mine water purification, pretreatment, nanofiltration