The invention discloses a preparation method and an application of corn peptide. The preparation method specially comprises the following steps: mixing corn gluten meal with an ethanol aqueous solution, wherein weight of the ethanol aqueous solution is 8-10 times of the weight of the corn gluten meal; inoculating Acetobacter aceti into the mixture so as to carry out fermentation; and adding acid proteases to carry out hydrolysis, so that a corn peptide which has a relatively good solubility under low-pH conditions is prepared; moreover, the corn peptide has relatively good activation-improving effects to alcohol dehydrogenase and acetaldehyde dehydrogenase.