Crude oil demulsifier is an oilfield chemical agent used for oil-water separation in petroleum production fluids. Its demulsification principle is that the demulsifier penetrates deeply and adheres to the interface of the emulsified droplets, replacing the original emulsifier and destroying the surface film, and coating the The droplets are released and coalesce, causing the oil and water phases to separate. Since the oil production technology has not changed from the initial water injection oil recovery to heavy oil thermal recovery, and then to alkaline water flooding, surfactant oil flooding, polymer oil flooding and tertiary oil recovery, through the colloid, asphalt and naphthenic acid in the crude oil, , fatty acids and salts, crystalline paraffin, and the emulsification of various artificially introduced surface-active substances, making the extracted crude oil appear in the form of an emulsion. In addition, due to the continuous advancement of new technologies, most oil fields in my country have entered a period of high water content. The crude oil emulsion has changed from CDE type to EDC type, which has increased the difficulty of crude oil demulsification and dehydration, and also made crude oil demulsifiers more complex in terms of composition, structure, and dehydration. The demulsification mechanism and other aspects have also undergone great changes. An ideal crude oil demulsifier should have strong surface activity, good wetting properties, sufficient flocculation ability, and good coalescence effect. While meeting the needs of oil fields and ensuring the demulsification and dehydration effect of crude oil, it also greatly promotes the development process of crude oil demulsifiers.