The utility model discloses an ammonia injection grid for flue gas denitration. The ammonia injection grid comprises an injection pipe and nozzle pipes, which are mutually connected, wherein the nozzle pipes are arranged on the injection pipe at intervals. The ammonia injection grid is characterized by further comprising a mixing pipe arranged above the nozzle pipes. According to the utility model, the mixing pipe is arranged right above the nozzle pipes, so that a spoiler effect on ammonia and air mixed gas ejected from the nozzle pipes can be produced and the ammonia gas and the flue gas can be fully and uniformly mixed; and a baffle effect on the smoke dust fallen from the upward side is further produced at the same time, the smoke dust fallen from the upward side is prevented from falling into the nozzle pipes and the nozzle pipes are prevented from blockage.