Chitosan quaternary ammonium salt is a cationic natural polymer obtained through chemical modification of chitosan, with the full name of hydroxypropyltrimethylammonium chloride chitosan. The product appears as a white or light yellow powdered solid with strong hygroscopicity. Chitosan quaternary ammonium salt exhibits excellent antibacterial properties, film-forming ability, conditioning effects, moisture retention, biocompatibility, biodegradability, flocculation, and anti-static properties. It has good water solubility, dissolving in both acidic and alkaline conditions with stable solutions. Chitosan quaternary ammonium salt can serve as a novel biological encapsulation material, protein drug carrier, gene delivery vehicle, enzyme immobilization agent, food preservative, natural clarifier for beverages and traditional Chinese medicine, treatment agent for digital printing fabrics, natural antibacterial agent, conditioning and moisturizing agent for hair care products, and more.