The chemical formula of ammonium sulfite is (NH4)2SO3. The aqueous solution is alkaline, white or light yellow, which is very corrosive to steel. The density of saturated solution is 1. 1995. It oxidizes easily in air. Decompose at 60-70℃. Mainly used in paper industry. It is also used in the daily chemical industry based on photosensitive materials. It can be used as an efficient absorbent to remove a small amount of hydrogen sulfide from coal gas, and can be used in medicine, photographic reducing agent, dye intermediate, paper making, food additive, water treatment and so on.