Nonionic emulsifiers are a class of emulsifying agents that do not dissociate in aqueous solution and carry no electrical charge on their hydrophilic groups. Their hydrophilicity primarily derives from polar groups such as polyoxyethylene chains, hydroxyl groups, or polyols that form hydration layers through hydrogen bonding with water molecules. The hydrophobic components typically consist of long-chain alkyl or alkylaryl groups, with precisely tunable hydrophilic-lipophilic balance values achievable by modifying polyoxyethylene chain lengths. Representative products include sorbitan fatty acid esters, polysorbates, fatty alcohol ethoxylates, and alkyl polyglucosides. They exhibit exceptional hardness resistance, outstanding chemical stability, and excellent compatibility with other emulsifier types, remaining largely unaffected by pH variations and electrolytes. Widely used in food processing, pharmaceutical preparations, cosmetics, and industrial products, they play crucial roles in formulations requiring mildness, safety, and stability.