Abstract: The experiment is carried out on thedrag reduction by riblets-surface.In order to study the drag of the underwater vehicle withriblets-surface, we use three models, with the 0.1\,mm riblets-surface,the 0.2\,mm riblets-surface and with velvet surface, respectively.From measarements with the models at various speeds, we can clearly see theeffect of drag reduction. The 8.3 percent drag is reduced by theriblets-surface.