The utility model discloses a fluidized bed evaporation reactor for flue gas desulfurization wastewater of a coal-fired power plant. The reactor comprises a reactor body, a hot air inlet is formed inthe bottom of the reactor body, a hot air outlet is formed in the top of the reactor body, and is characterized in that a filler layer is arranged in the middle of the reactor body and comprises seasonings and a filler screen, and a nozzle is arranged at the bottom of the filler layer and communicated with desulfurization wastewater through a pipeline; during working, filler in the filler layer forms a fluidized bed under the action of hot air, and desulfurization wastewater is sprayed into the fluidized bed through the nozzle for treatment. Desulfurization wastewater directly contacts with high-temperature filler in the fluidization process during operation, and is dried and caked on the surface of the filler, so that local low temperature caused by accumulation of the desulfurization wastewater at a certain position is avoided, and corrosion is avoided; according to the utility model, caking of desulfurization wastewater directly occurs on the surface of the filler, and in the subsequent fluidization process, the caking can be broken in the collision process, so that scaling in the reactor is avoided; the device is simple in structure and beneficial to manufacturing and installation.