The invention relates to a device and method for treating desulfurized waste water through flue multi-level evaporation.The device comprises a coagulating basin, a settling pond, a heat exchange pool, a water distributing main pipeline, a flue and a dust removing device, wherein a stirrer is arranged in the coagulating basin, a water inlet of the settling pond is connected with a water outlet of the coagulating basin, a water inlet of the heat exchange pool is connected with a water outlet of the settling pond, the water distributing main pipeline is connected with a water outlet of the heat exchange pool through a water pump, a compressed air inlet is formed between the water pump and the water distributing main pipeline, the water distributing main pipeline is connected with a plurality of water distributing branch pipelines, an atomizer is arranged at the tail end of each water distributing branch pipeline, the flue is a multi-section flue, horizontal sections and vertical sections of the flue are distributed alternately, each section of the flue is connected with the corresponding water distributing branch pipeline, an atomizer is arranged in each section of the flue, and the dust removing device is arranged at the tail end of the flue.The device has the advantages of low operation cost and stable system operation while zero emission of the waste water is achieved.