Ammonium sulfate, also known as ammonium sulfate, is the earliest nitrogen fertilizer produced and used at home and abroad. It is usually regarded as standard nitrogen fertilizer, and the nitrogen content is between 20% ~ 30%. Ammonium sulfate is a strong acid weak alkali salt, and the aqueous solution is acidic. Ammonium sulfate is a kind of nitrogen fertilizer and acid fertilizer in inorganic fertilizer. It is used alone for a long time, which makes the soil acidified and hardened and needs to be improved. Ammonium sulfate cannot be used to produce organic fertilizer. Moreover, acid fertilizer can not be used with alkaline fertilizer, and double hydrolysis is easy to lose fertilizer efficiency. In the 1960s, ammonium sulfate was the main variety of nitrogen fertilizer and one of the main sources of elemental sulfur providing crop nutrition . It was first made by neutralization with ammonia and sulfuric acid, but later the proportion of by-product ammonium sulfate became larger and larger. Now, all domestic by-products basically come from other industries, such as coking industry, caprolactam, sulfuric acid tail gas desulfurization, power plant desulfurization, acrylonitrile, methyl methacrylate, zinc oxide and other by-products. The by-product ammonium sulfate follows the principle of "treating waste with waste", realizes the comprehensive utilization of waste and achieves the purpose of energy conservation and emission reduction. Especially with the breakthrough of ammonia desulfurization project technology, the output of ammonium sulfate, the by-product of desulfurization in power plant, will increase significantly in the future.