The invention discloses a preparation method of a functionalized adjustable amphiprotic polycarboxylates cement grinding aid. The method comprises the following steps: according to a certain ratio, adding unsaturated polyether, unsaturated sulfoacid and water in a kettle; preparing unsaturated acid, a catalyst, a ligand and water into an aqueous solution A, and preparing an initiator and water into an aqueous solution B; heating the kettle to 75-95DEG C under the protection of nitrogen, and dropwise adding the aqueous solutions A and B at the same time for 3-5 hours; after the dropwise addition is finished, reacting under heat insulation condition for 1 hour; and after the reaction is finished, adding a certain part of sodium hydroxide for neutralization, and adding water for dilution until the concentration is 40% to obtain a finished product. In the invention, an active/controllable free radical polymerization and macromolecule design theory is adopted to research and develop the functionalized adjustable amphiprotic polycarboxylates cement grinding aid aiming at the effect required by the cement grinding aid, so as to prepare the product of the functionalized adjustable cement grinding aid.