Abstract: In order to give full play to the advantages of the sintering flue gas ammonia desulfurizationsystem to recycle the calcium desulfurization wastewater, this paper adds different volumes of the mainand second-stage calcium desulfurization wastewater to the ammonium sulfate mother liquor. The efectsof different addition conditions on the crystallinity , particle size distribution, C. V. value and morpholo-gy of ammonium sulfate crystals were studied. The following conclusions are obtained. With the increasein the amount of wastewater added, the crystallization amount of ammonium sulfate mother liquor increa-Sulfate ions and suspended solids in wastewater will increase the amount of ammonium sulfate crys-ses.tals. The average particle size and C. V. value of ammonium sulfate crystals changed irregularly afterthe addition of calcium desulfurization wastewater. The crystal morphology was generally more uniformthan that of the original mother liquor, and the particle size was relatively larger. Relevant research re-sults can provide new ideas for recycling of sintered flue gas calcium desulfurization wastewater.