The invention relates to a zero-emission treatment method and device for flue gas wet desulphurization waste water and belongs to the field of water treatment. The process includes the following steps that 1, a softening agent is added into the desulphurization waste water, the desulphurization waste water into which the agent is added enters a ceramic membrane filtration system, a concentrated solution is obtained and enters a sludge treatment system, and penetrant is obtained and enters a following process; 2, ceramic membrane produced water enters a multi-stage multi-section reverse osmosis system, reverse osmosis concentrated water enters a back-end process, and clear liquid is collected to be reused; 3, multi-stage multi-section reverse osmosis concentrated water enters a sodium bed system to remove residual hardness, and the water inflow requirement of the electrodialysis process is met; 4, sodium bed effluent further concentrates salt through an electrodialysis system, and electrodialysis fresh water enters a section of the reverse osmosis system to be reused; 5, electrodialysis concentrated water enters an evaporative crystallization process, crystal water enters a reuse water tank to be reused, and meanwhile a crystallized product crude salt is obtained to be treated. Zero emission of the desulphurization waste water is achieved through treatment.