Abstract: This present invention provides a new use of tanshinone derivatives as acetylcholinesterase inhibitors and in treating diseases associated with the depletion of acetylcholine such as cognitive impairment including Alzheimer's disease, insomnia, vascular dementia, memory loss, disorders of attention and other sleeping disorders. The active compounds commonly found in the root of Salvia genus, particularly Salvia miltiorrhiza, Danshen.