The utility model provides a coal-fired flue gas desulfurization and denitrification cooperative control device which is used for performing denitrification treatment of the flue gas treated by a limestone/gypsum wet desulphurization device to remove the pollutants such as SO2, NOx, mercury and the like in the coal-fired flue gas, and meets the new requirements on the atmosphere pollutant discharge. The device is provided with a desulfurization system, wherein the desulfurization system comprises a desulfurization slurry preparation system, a conveying system, a desulfurization absorption tower and a desulfurization byproduct treatment system; a denitrification system is also arranged behind the desulfurization system; and the denitrification system comprises a denitrification oxidant supply system, a denitrification reduction tower, a denitrification reducing agent supply system and a denitrification byproduct treatment system. By adopting the device provided by the utility model, the problems of blockage, ammonia escape and the like in an SCR operation process can be avoided, and the problem of space lack in ageing unit transformation can be solved. The device performs denitrification treatment on the flue gas after desulfurization treatment, avoids influence on the denitrification treatment process caused by SO2, does not need a denitrification inhibitor, and saves the operation cost. Meanwhile, the desulfurization reduction tower can reduce NOx into N2 and also has a function of mercury removal.