Flue gas cleaning device and method

The invention relates to a flue gas cleaning device and method which are used for flue gas cleaning. The flue gas cleaning device comprises a denitration tower and an oxidizing agent storage tank arranged at the outer part of the denitration tower; the bottom of the denitration tower is provided with a column bottom; a spraying layer A for spraying an oxidizing agent, a spraying layer B for spraying desulfuration by-products and a demisting layer are arranged in the denitration tower and above the column bottom in sequence from bottom to top; a flue gas inlet is formed between the column bottom and the spraying layer A and is formed in the wall of the denitration tower; the top of the denitration tower is provided with a flue gas outlet; the spraying layer A is communicated with the oxidizing agent storage tank by a pipeline; the spraying layer B is communicated with the column bottom by a circulation pump. The flue gas cleaning method comprises three steps: flue gas pre-treating, pre-oxidizing treating and denitration treating. When the flue gas cleaning device is used for cleaning the flue gas, the denitration efficiency is relatively high.