A preparation method of modified polyarylether (PAE) resin comprises the following steps of: reacting polyethylene polyamine and binary acid under effects of a catalyst to synthesize polyamine prepolymer, adjusting a solid content of the polyamine prepolymer tobe 20-30%, adjusting a pH value to be 8-10, adding carboxyl modifier, then adding epichlorohydrin, adding hydrochloric acid after a reaction is completed, adjusting the pH value to be 3-4 and finishing the reaction to obtain the modified PAE resin. Carboxyl is introduced in a molecular structure of the PAE resin, the carboxyl is used for balancing positive electricity carried by the PAE resin, and electric charge control of the PAE resin is achieved. Simultaneously, after paper is used, the carboxyl carried by the modified resin can form hydrogen bonds between fibers, the carboxyl in a structure of the PAE resin and epoxy functional groups and the like exist simultaneously, after the carried carboxyl forms the hydrogen bonds between fibers, a distance of the epoxy functional groups and primary amine groups and the like between different PAE resins is reduced, covalent bonds are conveniently formed, time needed by curing is shortened, and accordingly, paper forming humidity and strength are improved, and a humidifying and strength performance are strengthened.