The invention discloses an A<2> / O-biology synchronous nitrogen and phosphorus removal device for urban sewage. The device comprises a pre-anoxic pond, an anaerobic pond, an anoxic pond, an aerobic pond and a settling pond; the urban sewage is conveyed to the pre-anoxic pond and the anaerobic pond through a water inlet, a sewage lifting pump room with a coarse grille and a fine grille, an aeration grit basin, a water pump and a water inlet pipe; the interior of the pre-anoxic pond, the interior of the anaerobic pond and the interior of the anoxic pond are each provided with a submersible stirrer, the bottom of the aerobic pond is provided with an aerator, the aerobic pond is connected with the anaerobic pond through a nitration mixing reflux pipeline, the anoxic pond is connected with the anaerobic pond through an anoxic mixing reflux pipeline, one part of sludge at the bottom of the settling pond is conveyed to a sludge concentrating and dewatering room, and the other part of the sludge at the bottom of the settling pond is connected with the pre-anoxic pond through a reflux sludge pipeline. The invention further discloses an A<2> / O-biology synchronous nitrogen and phosphorus removal method for the urban sewage. According to the A<2> / O-biology synchronous nitrogen and phosphorus removal device and method for the urban sewage, the influence of nitrate on the anaerobic phosphorus releasing process is reduced or eliminated, the carbon source demands for anoxic denitrification nitrogen removing and anaerobic phosphate releasing are balanced, and the efficient nitrogen and phosphorus removal effects are achieved.