The invention discloses an integrated nitrogen and phosphorus recovery device in a struvite method, which relates to the field of environmental engineering water treatment and is a reactor for treating nitrogen and phosphorus-containing wastewater in a physicochemical method. Substances nitrogen and phosphorus in the wastewater are removed in a magnesium ammonium phosphate (struvite) form, and the substances are recovered and reused. The reaction device is in an integrated form, which comprises a precipitation zone, a mixing reaction zone, a crystal growth zone and a crystal trapping and water discharging zone from bottom to top sequentially, the mixing reaction zone is provided with a first-grade aerator, which is mainly a wastewater and reagent fully mixing and reacting zone; the crystal growth zone is provided with a second-grade aerator, which is mainly a struvite growth zone; in the precipitation zone, large-grain struvite crystals are mainly precipitated; and the crystal trapping and water discharging zone recovers the struvite crystals by a filter screen. In addition, the device uses external reflux to reinforce and to control the supersaturated rate of the struvite reaction, thus promoting the crystal growth. The device has simple technological process and has the advantages of short hydraulic retention time, high nitrogen and phosphorus recovery efficiency, high recovery pureness, little occupied area, low operation and maintenance cost and the like.