Alzheimer’s disease (AD), also known as senile dementia, is a degenerative disease of the central nervous system and is characterized by insidious onset and a chronic progressive course. It is the most common type of senile dementia. Studies have proved that the deposition of amyloid b (Ab) in the brain is one of the initiating factors correlated to the pathology of AD, and it acts as one of the critical factors leading to the onset of AD. A large number of long-term studies have shown that Ab may be a therapeutic target for a breakthrough in the treatment of AD. This review elucidates the important role of Ab in the development of AD, current research on the role of Ab in AD pathogenesis, and treatment of AD by targeting Ab.