Neutral polyester AKD sizing agent is one of newly-developed products in our company for the purpose of avoiding defects such as slow ripening, easy to be under machine moisture regain, high cost, ect. Common AKD emulsion using starch as emulsifier, which cause low retention rate, large dosage, slow ripening. Neutral polyester sizing agent adopts a new type of polymer emulsifier that our company developed independently which takes the petroleum resin as main raw material, and is supplemented by other cationic surfactant, . The emulsifier is polymer, high cationic charge density and thus the emulsification has highly efficiency, uniform dispersion, and small particle size. The manufactured AKD sizing agent ripens fast with high efficiency and the dosage can be reduced more than 10% compared with ordinary AKD products.