The invention relates to a counter-current forced mixing ammonia spraying apparatus, comprising a forced mixing dustproof plate, a support, nozzles, ammonia spray grid branch pipes, an ammonia spray grid main pipe and feed pipes; the nozzles are arranged on the ammonia spray grid branch pipes, and the ammonia spray grid branch pipes are connected to the feed pipes through the ammonia spray grid main pipe; the nozzles are opposite to the flowing direction of smoke; the forced mixing dustproof plate is arranged 40-60 mm before the nozzles through the support and is less than the nozzles in area. The counter-current forced mixing ammonia spraying apparatus has the advantages that counter-current forced mixing provides improved mixing uniformity of a reducing agent and smoke, the apparatus is simple and highly reliable, the dustproof mode is reasonable, ash blocking of the nozzles is avoided, investment cost is low, and no adverse influence is caused to a denitration system.