The invention discloses nimodipine microemulsion injection containing amino acid and a preparation method of the nimodipine microemulsion injection. The nimodipine microemulsion injection comprises nimodipine, oil for injection, phospholipid for injection, a coemulsifier, amino acid, glycerin and water for injection, wherein the content of the amino acid is 0.01%-3%. The amino acid is added to be taken as a protecting agent of nimodipine, a dehydrogenation reaction is avoided by protecting dihydropyridine in medicine molecules, production of nimodipine degradation products is reduced, the impurity limit is reduced, the chemical stability of medicine-carrying submicron emulsions is improved, and potential toxic risk due to high impurity content is effectively avoided.