The invention discloses a graft-modified macromolecular filter membrane for water treatment and a method for preparing the same. The filter membrane takes a macromolecular membrane material as a grafting substrate, wherein the chemical structure of a macromolecular filter membrane interface comprises an electroneutral acid-base matching network. The preparation method comprises the following steps: 1) preparing a modified macromolecular membrane material of a branched chain containing negatively charged acidic groups by a pre-irradiation grafting method; 2) preparing a modified macromolecularmembrane material of a branched chain containing positively charged alkaline groups by the pre-irradiation grafting method; 3) and dissolving the modified macromolecular membrane material of the step1) and the modified macromolecular membrane material of the step 2) in solvent in the molar ratio of the contained acid-base groups of 1 to 1, and adding a pore-forming agent so as to prepare electroneutral membrane casting solution. The invention provides a method for improving the performance of the filter membrane fully, and prepares a permanently pollution resistant filter membrane. The filtermembrane has the characteristics of high water flux and high retention rate, and has significant economic benefit.