The present invention provides a crystalline form of dextral oxiracetam. The crystalline form has a diffraction peak when a diffraction angle, 2θ, is 17.12±0.2°, 18.88±0.2°, 19.24±0.2°, 21.18±0.2°, 24.88±0.2°. The crystalline form having oxiracetam can promote synthesis of phosphorylcholine and phosphoethanolamine, boosts cerebral metabolism, has a stimulating function on a specific central nervous pathway by means of a blood-brain barrier, improves the intelligence and memory, has an obvious effect on a memory dysfunction, and has special biologic activity in the field of sedation and the antiepileptic field. The method for preparing the crystalline form is simple and is suitable for industrial production.
