The invention relates to the field of wastewater treatment, particularly to a method and an apparatus for zero-emission treatment of desulfurization wastewater. The method comprises: adding calcium hydroxide to desulfurization wastewater treated by a triple box, adjusting the pH value to achieve more than 11 to form magnesium hydroxide; precipitating, and removing the magnesium hydroxide and insoluble calcium hydroxide; adding sodium sulfate to generate calcium sulfate, precipitating, and removing the calcium sulfate; adding sodium carbonate to form calcium carbonate, precipitating, and removing the calcium carbonate; sequentially carrying out ultra-filtration treatment, nano-filtration salt separation treatment and reverse osmosis concentration treatment; and carrying out evaporation concentration crystallization treatment to obtain a sodium chloride crystal. The apparatus comprises a magnesium removal reaction box, a precipitation box, a coarse calcium removal box, a fine calcium removal box, a suspension concentration box, a tubular ultra-filtration device, a nano-filtration salt separation device, a reverse osmosis device, and an evaporation crystallization device, wherein thedevices are sequentially connected. With the method of the present invention, the softening cost is reduced, and the complete recycling of water resources and the production of high-quality sodium chloride can be achieved.