The invention discloses an imidazole ionic liquid electromigration antirust agent and a preparation method thereof. By the electromigration antirust agent, a perssad which has static effect or coordination on iron is introduced on an imidazole ring, and adsorption capacity can be improved, so that the antirust efficiency is improved effectively. The preparation method comprises the following steps: (1) preparing N-alkyl substituted imidazole by using imidazole and halohydrocarbon of C1-C12; and (2) reacting the N-alkyl substituted imidazole with a quaternized reagent to obtain the imidazole ionic liquid electromigration antirust agent. The synthesis method of the imidazole ionic liquid electromigration antirust agent provided by the invention is simple, harsh conditions are not required, antirust efficiency is excellent, the antirust agent can be migrated into a test piece under the effect of an electric field, and volume of migration is not affected by the pH value of the test piece.