Method and system for defluorinating mine water

A method for defluorinating mine water removes fluorine in the mine water through a fluorine removal agent, the fluorine removal agent comprises a main fluorine removal agent, and the main fluorine removal agent is fly ash. The invention also provides a system for defluorinating the mine water by using the method. The system comprises a first underground reservoir, a mine water injection pipeline, a fly ash adding device and a mine water discharge pipeline; the fly ash adding device comprises a stirring pool and a grouting pump; the stirring pool is used for stirring the added fluorine removal agent and water to obtain a mixture; the feeding end of the grouting pump is connected to the discharging port of the stirring pool, and the discharging end of the grouting pump is connected to the mine water injection pipeline and used for pumping the mixture to the mine water injection pipeline; the mine water injection pipeline is connected to the water injection port of the first underground reservoir and is used fo