Alkyl trimethylammonium salt type cationic surfactant is prepared by reacting higher fatty amine and methyl chloride in the presence of sodium hydroxide. This surfactant is a long-chain alkyl or hydrocarbyl group (usually 8 to 22 carbon atoms), three short-chain alkyl (1 to 7 carbon atoms) structure, such as 1231 (dodecyl) Trimethyl ammonium chloride), 1431 (tetradecyl trimethyl ammonium chloride), 1631 (hexadecyl trimethyl ammonium chloride), 1831 (octadecyl trimethyl ammonium chloride) . This surfactant is easily soluble in water, transparent, and has good surface activity. It can be used as an antistatic agent for external coating such as shampoos, bactericidal detergents, polystyrene resins, and antistatic agents for fibers. Levelling agent, demulsifier and dispersant, etc.