Abstract: Evaporation-cooling coupled crystallization process of ammonium sulfate was studied.Effects of physicochemical environment of crystalline system and crystallizing process conditions，such as additive policies and dosage，crystallizing temperature，seeding policies，pH，evaporating rate，and stirring rate，on the particle size and crystal habit of ammonium sulfate were investigated systematically.Based on experimental researches，the optimum crystallizing conditions were confirmed，under which the granular ammonium sulfate crystals with particle size of 2~2.5 mm was obtained.Granular ammonium sulfate crystals had good physical properties，such as high purity，good fluidity，not easy to kick up dust，not easy to agglomerate，and easy to spread and mix.

Key words: ammonium sulfate；crystallization；particle size；crystal habit