Flue gas denitrification method

The invention discloses a flue gas denitrification method. The method comprises the following steps of: feeding the flue gas into a desulphurization device after dust removal, wherein the desulphurization device comprises three to six layers of spraying layers; injecting a strong oxidizer into the flue gas entering a spraying tower by pressurization; contacting the flue gas with desulphurization slurry to perform heat transfer reaction and mass transfer reaction in the spraying layers; washing off sulfur dioxide in the flue gas and reacting the sulfur dioxide with calcium carbonate in the desulphurization slurry; settling plaster serving as a final product down to the bottom of the desulphurization device; discharging the flue gas from which the sulfur dioxide is removed into a chimney from a flue on the top of a desulfurizing tower; and finally discharging the flue gas into atmosphere by the chimney. In the method, the NOx in the flue gas is oxidized into a water-soluble valence state such as NO2, N2O3, N2O5 and the like by adopting the strong oxidizer and then gathered from the desulfurizing tower by a semi-dry method or wet method, so that the aim of removing the nitrogen oxide is fulfilled.