The invention relates to a struvite circulating crystallization method for treating synthetic ammonia wastewater. The method comprises the following steps of: A, adding soluble phosphate and magnesium salt into the synthetic ammonia wastewater at the ammonium nitrogen concentration of 1,000-2,065mg / L; B, adding alkali into the acquired struvite solid, and performing pyrolysis at the temperature of between 80 and 100DEG C for 1 to 3 hours; C, treating the synthetic ammonia wastewater by using a pyrolysis solid product, and adding a small amount of magnesium salt, wherein ammonia generated in the pyrolysis process is absorbed by a dilute acid solution, and the obtained ammonium salt is used as a raw material for producing a fertilizer; and D, using struvite which cannot be recycled as a sustained-release fertilizer. For the synthetic ammonia wastewater at the ammonium nitrogen concentration of 1,000-2,065mg / L, the struvite can be recycled for 3 to 6 times, the ammonia nitrogen removal rate is higher than 87 percent, the ammonium nitrogen concentration of effluent is lower than 200mg / L, agents are saved through recycle, and nitrogen resources are recycled. The pretreated wastewater meets the requirement of an A / O biochemical treatment process on nitrogen and phosphorus, and can be subjected to biochemical treatment further.