Ester-based quaternary ammonium salt is a new type of cationic surfactant with excellent softening and antistatic properties, resistance to yellowing, good water solubility, softness and smoothness, rewetting properties, compatibility, and low foaming. It can be used for the softening and finishing of bleached fabrics; it can be applied in daily chemical products, fabric softeners, detergents, and cleaning agents; it can be stored at a high concentration of 20% without stratification, and can be used alone or in combination with silicone oil; it is free of APEO and formaldehyde, easily biodegradable, and an environmentally friendly product. It is widely used in the finishing and softening treatment of dyed and finished cotton, linen, silk, wool, polyester, acrylic, and other fiber yarns and fabrics.