1. Used in the microanalysis of tellurium and niobium and in the preparation of developer solutions. It is also used as a reducing agent. 2. Used as a stabilizer for artificial fibers, a fabric bleach, a photographic developer, a dye and bleach deoxidizer, a fragrance and dye reducing agent, and a papermaking lignin remover. 3. Used as a general analytical reagent and photoresistor material. 4. Used as a reducing bleaching agent, it has a bleaching effect on foods and a strong inhibitory effect on oxidases in plant-based foods. my country stipulates that it can be used in preserved fruits, with a maximum usage of 2.0g/kg. It can also be used in glucose, liquid glucose, table sugar, rock sugar, malt sugar, candy, bamboo shoots, mushrooms and canned mushrooms, grape and blackcurrant concentrates, with a maximum usage of 0.60g/kg. The residual content (calculated as SO2) in bamboo shoots, mushrooms and canned mushrooms, preserved fruits, grape and blackcurrant juice concentrates must be ≤0.05g/kg; the residual content in potato starch must be ≤0.03g/kg; the residual content in biscuits, sugar, vermicelli, and other products must be less than 0.1g/kg; the residual content in liquid glucose must not exceed 0.2g/kg. 5. In the printing and dyeing industry, it is used as a deoxidizer and bleaching agent in the scouring of various cotton fabrics to prevent localized oxidation of cotton fibers that affects fiber strength and improve the whiteness of the scouring product. In the photographic industry, it is used as a developer. In the organic industry, it is used as a reducing agent in the production of m-phenylenediamine, 2,5-dichloropyrazolone, anthraquinone-1-sulfonic acid, 1-aminoanthraquinone, and sodium aminosalicylate to prevent oxidation of semi-finished products during the reaction process. In the papermaking industry, it is used as a lignin remover. In the textile industry, it is used as a stabilizer for man-made fibers. In the electronics industry, it is used in the manufacture of photoresistors. In the water treatment industry, it is used to treat electroplating wastewater and drinking water. 6. In the food industry, it is used as a bleaching agent, preservative, loosening agent, and antioxidant. It is also used in pharmaceutical synthesis and as a reducing agent in the production of dehydrated vegetables. 7. It is used in the preparation of cellulose sulfite, sodium thiosulfate, organic chemicals, and for bleaching fabrics. It is also used as a reducing agent, preservative, and dechlorinating agent. 8. In laboratories, it is used to prepare sulfur dioxide.