The invention relates to the field of chemical organic synthesis, in particular to a method for synthesizing 2-acetyl pyrazine. The method comprises the following steps: (1) preparation of a Grignardreagent: adding metallic magnesium, an anhydrous polar solvent, elemental iodine and methyl chloride into a pressure vessel, and stirring to prepare the Grignard reagent; (2) adding reaction: adding 2-cyanopyrazine, tetrahydrofuran, a catalyst and the Grignard reagent into a reactor, and refluxing and condensing to obtain an intermediate product; (3) hydrolyzing: adding water into the intermediateproduct, adjusting the pH value by using dilute acid, stirring and refluxing, and then adjusting to be neutral; and finally, extracting with toluene; and (4) aftertreatment: desolventizing a tolueneextracting solution, dissolving desolventized solid with ethanol, adding activated carbon, filtering, and cooling to obtain a white solid P1; and recrystallizing with the ethanol to obtain the 2-acetylpyrazine. According to the method, a monovalent copper salt is adopted as a catalyst, the yield of 2-acetylpyrazine is increased to be 69%, meanwhile, the reaction speed is increased, and the synthesis reaction temperature is also reduced.