The invention discloses a synthesis method and application of a sulfonamide dimethylpyrimidine molecularly imprinted polymer. The synthesis method comprises the steps: adopting sulfamethazine as a template molecule, adopting methacrylic acid and diallylamine as mixed functional monomers and divinylbenzene as a cross-linking agent under the condition of a methanol solvent, and performing a precipitation polymerization reaction in a constant-temperature bath under the action of an initiator so as to prepare the sulfonamide dimethylpyrimidine molecularly imprinted polymer. The sulfonamide dimethylpyrimidine molecularly imprinted polymer has a good recognition ability for SMZ, the effects of separation and enrichment of SMZ are achieved through specific SMZ adsorption, and good specific adsorption abilities are achieved.