The invention discloses a polyether de-emulsifier and a W/O-type crude oil emulsion demulsification dehydration method using the same. A preparation method of the polyether de-emulsifier comprises that 1, an amino group-terminated polyamide-amine type molecule is grafted to an ester group-terminated polyamide-amine type molecule, wherein a mole ratio of the amino group-terminated polyamide-amine type molecule to the ester group-terminated polyamide-amine type molecule is 3-50: 1 and the amino group-terminated polyamide-amine type molecule and the ester group-terminated polyamide-amine type molecule belong to generation of less than 3.0, and 2, the product obtained by the step 1 and an epoxy compound undergo a reaction. The preparation method of the polyether de-emulsifier has simple synthesis processes and can be easily industrialized. The polyether de-emulsifier has a high branch structure. The test result in the embodiment shows that the polyether de-emulsifier has excellent demulsification effects.