A composition comprising tanshinone compounds selected from the group consisting of miltirone, 1,2-didehydromiltirone, tanshinone IIA, tanshinone I and dihydrotanshinone I isolated from Salviae miltiorrhizae Bunge showing potent inhibiting effect on the aggregation and toxicity of beta-amyloid and recovering activity of memory learning disorder confirmed by Y maze study and Passive Avoidance study. Therefore it can be used as the therapeutics or health food for treating and preventing cognitive function disorder with safe.