The invention provides a preparation method of antioxidation active peptide enzymatic hydrolysate for largehead hairtail. The preparation method comprises the operation steps of (1) performing pretreatment; (2) performing deodorization; (3) performing defatting; and (4) performing enzymolysis. The preparation method has the beneficial effects that fishy smell substance characteristic components on bodies of the largehead hairtail are trimethylamine, and deodorization fluid used in the preparation method not only can react with the trimethylamine to form quaternary ammonium salt but also can dissolve the trimethylamine, so that the deodorization effect is quite obvious; ethyl acetate is used for defatting, so that the defatting rate is high; polypeptide obtained by enzymolysis of largehead hairtail protein through double enzymes is adopted, so that the capacity for removing DPPH free radicals and hydroxyl radicals is high, and the antioxidation capability is high; and the obtained polypeptide is small in molecular weight, is easy to absorb by human bodies, and is suitable for application to the fields of foods, medicines and cosmetics. The method is simple to operate and low in cost, the added value of the largehead hairtail is increased, and the method is suitable for mass production.