Preparation of polymer flooding produced fluid demulsifier

The invention provides a preparation method of a polymer flooding produced fluid demulsifier, which mainly comprises the following steps: condensing p-tert-butyl phenol, polyethylene polyamine and formaldehyde to obtain a thermoplastic phenol amine resin of which the molecular weights are within a certain range; sequentially and proportionally carrying out ring-opening polymerization on the resin, epoxyethane and propylene oxide; mixing the synthesized products with different molecular weights in a certain mass ratio, and regulating the pH value with acetic acid; and finally, cross-linking with dicarboxylic acid to obtain the final product. The invention aims to solve the problems of severe oil/water emulsification, greater difficulty in oil-water separation, high oil content in dehydrated water and the like in the polymer flooding produced fluid, and the problem that the dehydration effect of the conventional demulsifier on the produced fluid is not ideal.