The invention discloses a synthesis method for macromolecular cationic bleaching activators and belongs to the field of fine chemical engineering. According to the method, tertiary amine containing carbon-carbon double bonds, 4-chloromethyl benzoyl chloride and lactam are taken as intermediates for synthesizing a series of cationic bleaching activators with quaternary ammonium salt groups. Such bleaching activators have strong affinity to the materials with surfaces under electronegative state in aqueous solutions, can react with hydrogen peroxide on the material surfaces so as to generate active peroxy acids, can bleach the materials under low temperature and can effectively remove the pigment impurities from the material surfaces. The cationic bleaching activators can be used for industrial bleaching and domestic washing of textiles.