The invention relates to a recycled 
flue gas desulfurization and denitration method, which sequentially comprises the following steps of: introducing 
flue gas of SO2 and 
NOx into a desulfurizing 
tower, and absorbing the SO2 with a desulfurizing agent (barren liquor) in the desulfurizing 
tower; desorbing the desulfurizing agent (rich liquor) which absorbs the SO2 through a multi-effect 
evaporator,releasing the SO2 gas, and concentrating the SO2 gas into liquid SO2 through condensation 
drying; making the desulfurized 
flue gas enter a denitration 
tower, injecting 
gaseous ozone from an 
ozone generator, oxidizing the NO in the 
flue gas, absorbing the oxidized NO by using a denitrifier to form 
nitrate; crystallizing and separating out the 
nitrate in the solution after the 
nitrate reaches certain concentration, and filtering and 
drying to obtain the nitrate product. The method turns the wastes into wealth, and the SO2 and 
NOx in the 
flue gas are recycled by higher-additional value liquid SO2 and nitrate products, so that the recycling and value maximization in the desulfurization and denitration process is realized. Due to the adoption of the technical scheme, the high desulfurization and denitration rate can be achieved, the desulfurization rate is over 96 percent, the denitration rate is more than 90 percent, and the purity of the nitrate product is over 96 percent. The method hasthe advantages of simple desulfurization and denitration process, low investment, and low operation cost for desulfurization and denitration, and solves the problems that the conventional desulfurization and denitration process has high cost, generates a 
side product of a mixture of 
sulfuric acid (
sulfate) and 
nitric acid (nitrate), and has low additional value.