The utility model provides a flue gas spouts device of ammonia denitration, including flue (3), the flow direction along the flue gas in flue (3) has set gradually the mixed unit of flue gas (5) and reaction zone catalyst (2), and the mixed unit of this flue gas (5) can make this flue gas mix, still is equipped with reductant jet (8) that are used for to spraying the reductant in the flue (3) between the mixed unit of this flue gas (5) and reaction zone catalyst (2). The gas composition concentration profile tend to even on the mixed unit of flue gas among the the device can make the flue cross -section. Under the prerequisite that does not increase NOx measurement station quantity, performance reductant flow automatic control's effect realizes deNOx systems optimal operation.