Oil-soluble demulsifier as well as preparation method and application thereof

The invention provides an oil-soluble demulsifier as well as a preparation method and application thereof, and belongs to the field of chemicals for recycling and treating water-containing waste liquid of petroleum industry and petrochemical oil plants. The preparation method comprises the following steps: mixing trimethylolpropane, phenol and polyethylene polyamine to perform a first polymerization reaction, mixing a first polymerization product, potassium hydroxide and propylene oxide to perform a second polymerization reaction, mixing the second polymerization product and ethylene oxide to perform a third polymerization reaction, neutralizing the third polymerization product until the pH value is 6-7, and performing a second polymerization reaction to obtain a second polymerization product; and mixing the neutralized material with mixed benzene, and carrying out a blending reaction to obtain the oil-soluble demulsifier. The potassium hydroxide is used as the catalyst to carry out the second polymerization