(S)-4-hydroxyl-2-keto-1-piracetam crystal form III (called (s)- oxiracetam crystal form III for short) has diffraction peaks at diffraction angles 2θ, wherein the diffraction angles 2θ are equal to 10.54°, 13.70°, 14.44°, 15.60°, 17.12°, 18.88°, 19.24°, 20.66°, 20.84°, 21.18°, 21.82°, 22.94°, 23.24°, 24.88°, 27.20°, 27.48°, 28.24°, 30.46°, 30.80°, 31.52°, 32.00°, 32.34°, 32.90°, 33.20°, 34.40°, 34.62°, 37.30°, 37.50°, 38.28°, 38.96°, and 40.02°. The (S)-oxiracetam crystal form III of the present invention has an obvious effect on memory dysfunction, is dissolved in water fast, has high bioavailability, and can be used to prepare various pharmaceutical compositions. The (S)-oxiracetam crystal form III obtained by using the preparation method of the present invention is high in purity. The preparation method of the application of the present invention is performed in a mild condition, is easy in operation, introduces less impurities, has desirable reproducibility, is easily controlled during production, and is applicable to industrial production.Cette invention concerne la forme cristalline III du (S)-4-hydroxyl-2-céto-1-piracétam (abrégée en forme cristalline III du (s)- oxiracétam) qui présente des pics de diffraction aux angles de diffraction 2θ, lesdits angles de diffraction 2θ correspondant à 10,54°, 13,70°, 14,44°, 15,60°, 17,12°, 18,88°, 19,24°, 20,66°, 20,84°, 21,18°, 21,82°, 22,94°, 23,24°, 24,88°, 27,20°, 27,48°, 28,24°, 30,46°, 30,80°, 31,52°, 32,00°, 32,34°, 32,90°, 33,20°, 34,40°, 34,62°, 37,30°, 37,50°, 38,28°, 38,96°, et 40,02°. La forme cristalline III du (S)-oxiracétam selon linvention a un effet flagrant sur le dysfonctionnement de la mémoire, se dissout rapidement dans leau, a une biodisponibilité élevée, et peut être utilisée pour préparer diverses compositions pharmaceutiques. La forme cristalline III du (S)-oxiracétam obtenue à laide du procédé de préparation selon linvention est de pureté élevée. Le procédé de préparation selon linvention est mi
