A device and a method for realizing deep denitrification control of urban sewage by short-range denitrification behind a PNA system belong to the field of biological treatment of sewage. The deep denitrification control of urban sewage is operated in a sequencing batch reactor in an aerobic-anoxic manner. Sewage with a C/N ratio enters a PNA-PNAD system. AOB and Anammox act together in the aeration stage to realize autotrophic nitrogen removal of NH<4><+>-N in raw water. The concentrations of ammonia nitrogen and nitrate are monitored by an online probe, and when the two values are close toeach other, the aeration is stopped, the aerobic stirring is started, and an organic carbon source is added to make a ratio of COD/NO<3><->-N be 3-5. Denitrifying bacteria and Anammox synergisticallyact in the anoxic stirring stage to remove nitrogen, and the remaining NH<4><+>-N and NO<3><->-N are further degraded to finally achieve deep denitrification of PNA-PNDA urban wastewater. The problemof the system destruction caused by the competitive growth of nitrite-oxidizing bacteria (NOB) due to two low ammonia nitrogen in effluent water when the PNA is applied to the urban sewage is solved;and the problem that the nitrate content of PNA treated urban sewage effluent is high and the content of ammonia nitrogen cannot be too low is solved.