The present invention provides a deep sea water extract and a method for inhibiting the proliferation of Helicobacter pylori strains using the deep sea water extract, wherein the deep sea water extract has an organic component with a molecular weight of 685 to 690, 733 to 738 and 1,070 to 1,075. The deep sea water extract of the present invention can be applied in the prevention and treatment of H pylori infection.