Sodium Metabisulfite (SMBS) is a white or pale yellow crystalline powder at room temperature, with a strong, pungent sulfur dioxide odor. It is readily soluble in water and rapidly decomposes into sodium bisulfite in aqueous solution, resulting in an acidic medium. Its chemical properties are primarily characterized by strong reducing power, weak acidity, and the ability to undergo addition reactions: it is easily oxidized in air, decomposes upon heating to release sulfur dioxide, and can participate in addition reactions with carbonyl compounds such as aldehydes and ketones. Leveraging these characteristics, its primary applications include serving as an efficient reducing agent, bleaching agent, preservative, and antioxidant. It is widely used in the food industry (e.g., in winemaking and for color preservation and preservation in fruit and vegetable processing), water treatment (chlorine removal, deoxygenation), textile dyeing and printing (reduction clearing, dechlorination), and chemical synthesis (e.g., sulfonation reactions), among other fields.