NOVELTY - Recovering struvite from in wastewater with high concentration ammonia nitrogen, comprises (i) performing transformation of struvite, carrying out real time monitoring of the granulating main body, opening feeding tube containing 5 feeding ports, and feeding alkali, waste water and magnesium chloride solution into each inlet opening, and automatically regulating pH; and (ii) adjusting struvite recovery process by taking waste water containing ammonia nitrogen, phosphate-phosphorus, and magnesium chloride, performing real time monitoring, mixing nitrogen, phosphorus and magnesium solution.    USE - The method is useful for recovering struvite from in wastewater with high concentration ammonia nitrogen (claimed).    DETAILED DESCRIPTION - Recovering struvite from in wastewater with high concentration ammonia nitrogen, comprises (i) carrying out transformation of struvite in a recovering device comprising a granulating main body which is designed into three sections by a bottom-feeding tube, where the three sections of a granulating tube and a sedimentation tube part forms a three-stage conical fluidized bed reactor, and the bottom of the sedimentation tube and the top part of the granulation tube are fixedly connected through an interface being a frusto-conical-shape interface, having an inclined angle ( theta ) of 25-45 degrees , and the shape of the granulating tube is a small cone-shape, and the outer diameter of the a large end and the small end is 3:1, the length of the small outer diameter end is 50:1, and a pH probe is set in the inner side of the granulating tube, and then carrying out real time monitoring of the granulating main body by pH probe of a pH controlling device, and opening the feeding tube containing 5 feeding ports, where the feeding tube is provided with a feeding port, and 2 among 5 feeding ports are return water inlets, and a water pump is connected to a secondary sedimentation tank by the feeding tube, and feeding alkali (remaining amount), waste water and magnesium chloride solution into each inlet opening, and automatically regulating the pH of the alkali port by a pH regulating pump connected to the alkali slot, where the ratio of the length of three sections of precipitation tube, granulating tube and feeding tube is 2:5:1; and (ii) adjusting struvite recovery process by taking waste water containing 1000-1600 mg/l ammonia nitrogen, 1500-2400 mg/l phosphate-phosphorus, and magnesium chloride solution having 1260-2380 mg/l magnesium ion concentration in a magnesium salt tank, and feeding alkali liquid into the inner slot through a feeding tube, and feeding waste water and magnesium chloride solution by an inlet, pumping the mixture into the feeding pump, and transferring into granulating tube, where the mol ratio of ammonia nitrogen, phosphate-phosphorus and magnesium chloride solution is 1.5:1:1.1-1.5:1:1.3, and then opening the 2 returning water inlet connected to the reflux pump, allowing the waste water and magnesium chloride solution to flow from the secondary sedimentation tank into the granulating main body by sedimentation tube, and controlling the reflux ratio to 12-30, and carrying out real time monitoring of the granulating main body by pH probe of the pH controlling device, injecting alkali solution into the granulating main body by the pH regulating pump containing pH meter, where the pH of the granulating main body is 6-7, and mixing nitrogen, phosphorus and magnesium solution in the granulating main body, and obtaining struvite crystals during the first minute, and continuously operating a micro-device for 3 days, and producing few large particles of struvite, and simultaneously closing the granulating tube by a valve, opening an outlet valve located at the bottom part of the feeding tube, and removing struvite crystals, and periodically recovering struvite particles from the bottom of the granulation main body, removing the struvite crystals located at the bottom by detection process, and obtaining spherical struvite with smooth surface having diameter of 3-8 mm, and having high purity of more than 97.5%, hardness of 20.3 plus minus 1 kg/mm2, and arranging the struvite crystal according to arrangement rule and are orderly-tightly arranged.