Used as a raw material for the manufacture of magnetic iron oxide, iron oxide red and iron blue pigment, polymerized iron sulfate, etc. In the water treatment industry, it is used to clarify the turbidity. It is used as a coagulant to clarify turbid water in water treatment industry, and used to treat chromium-containing wastewater and cadmium-containing wastewater. It is used as reducing agent and catalyst in chemical synthesis. Used as blood tonic and local astringent in pharmaceutical industry. Used as reducing agent in indigo dyeing in printing and dyeing industry. It is also used as wood preservative, feed additives, herbicides and drugs to prevent and control plant green pigment deficiency. Food grade ferrous sulfate can be used as iron nutritional supplements and fruit and vegetable coloring agent, and used to maintain the fresh color of pickled products.