Abstract: The invention discloses a new use of ?-Mangostin in medicine, which is application of ?-Mangostin in preparation of medicaments for Alzheimer's disease. Under the new working concentration, ?-Mangostin showed the capability to inhibit the aggregation and deposition of A?. Moreover, it displayed the neuroprotective effect against neurotoxicity caused by A? oligomer, which maintained normal morphology of mammalian neuron cells, enhanced their normal physiological function, and realized the intervention in pathological process of Alzheimer's disease. The invention provided a new approach to treat Alzheimer's disease.