Composite type crude oil demulsifier and preparation method thereof

The invention discloses a composite type crude oil demulsifier and a preparation method thereof. The composite type crude oil demulsifier comprises active ingredients of compounds in a formula I and aformula II, wherein R1 is alkyl having 10 to 24 carbon atoms; PO is -(CH2-O-CH2CH2)-; EO is -(O-CH2CH2)-; R2 is alkyl with the number of the carbon atoms more than 9; Ar is aryl; m is between 10 and500; and n is between 10 and 500. The invention also discloses the method for preparing the composite type crude oil demulsifier. The composite type crude oil demulsifier has excellent surface property and infiltrability, can reach an oil-water interface quickly and replace natural interface active substances to form a novel unstable oil-water interface film, has excellent demulsification performance on crude oil emulsion, and can be applied in the fields of crude oil extraction, petroleum refining and the like.