The invention discloses a 2Hthiazolo [3, 2b] 1, 2, 4triazine 3, 7diketone derivative as shown in a general formula I or pharmaceutically acceptable hydrate and salt thereof, the 2Hthiazolo [3, 2b] 1,2, 4triazine 3, 7diketone derivative comprises stereoisomers or tautomers thereof, and R1 and R2 in the general formula I can be optionally selected from one, two or three independently selected fromhydrogen, alkyl, alkoxy, halogen, hydroxyl, acetyl, propionyl, nitro or trifluoromethyl. The 1, 2, 4-triazine 3, 7diketone derivative has an obvious inhibiting effect on acetylcholin esterase, and isused for enhancing the memory of a patient suffering from dementia and Alzheimer's disease. The invention also relates to a preparation method of the compound and the application of the compound in preparation of drugs for treating Alzheimer's disease.