Sodium sulfide, also called sodium sulfide dihydrate or sodium polysulfide, is an inorganic salt with strong moisture absorption, and is easily soluble in water. It can generate sodium hydroxide and sodium hydrosulfide by hydrolysis.

Its aqueous solution is strongly alkaline, and has strong corrosiveness, therefore, it can be used to produce sulfur dyestuff in dye industry like sulfur black, sulfur blue or dye intermediate reducing agent and mordant, or is used as flotation agent of ore in nonferrous metallurgy industry, as depilating agent for raw hides in the leather industry, or as digester aid in papermaking industry, and is widely used for production of sodium thiosulfate, sodium bisulfide, sodium polysulfide in sodium sulfide industry, as well as textile, dyestuff, rubber and pharmaceuticals.

As one of important industrial products of organic salt, it has a wider range of application and development prospect for product conversion. As production process is updated, the product quality is continuously improved, and it will become one of important export chemical products for foreign exchanges.