The invention belongs to the technical field of zero discharge of desulfurization wastewater from power plants. A device capable of realizing zero discharge of desulfurization wastewater is characterized by comprising a raw water regulating pond, an alkalization module, a sludge separating and recycling module, a calcium removal module, a reduction module and a curing module; the desulfurization wastewater flows into the alkalization module for a flocculation reaction after the volume is adjusted by the raw water regulating pond, magnesium and sulfate radical ions in the desulfurization wastewater are deposited to form floccule, the flocculated desulfurization wastewater flows into the sludge separating and recycling module for sludge sorting, the sorted sludge is treated separately, the sorted desulfurization wastewater is subjected to salinity testing, the low-salinity desulfurization wastewater flows back to a desulphurization island, the high-salinity desulfurization wastewater flows into the calcium removal module, so that the concentration of calcium ions in the desulfurization wastewater is reduced, and water is softened; the pH of outflow water from the calcium removal module is regulated until the water is neutral, and the water flows into the reduction module which adopts a nanofiltration system and a reverse osmosis system for desalination. The device can realize zero discharge of the desulfurization wastewater.