Abstract: Alzheimer’s disease (AD) is unknown cause progressive degenerative diseases of central nervous system. It is a serious threat to the health of the elderly people. The diagnosis is mainly based on pathological examination after death. With the wide application of positron emission tomography (PET) imaging in clinic, in vivo noninvasive imaging diagnosis of AD at the early stage become possible. PET imaging mainly depends on the positron-labeled imaging agents. The PET imaging agents can be used in the early diagnosis and differential diagnosis on AD include several kinds: PET traces for glucose metabolic, PET traces combined with amyloid proteinplaques,tau protein, neurotransmitter and receptor, activation of microglia and PET traces for cell apoptosis.The research progress of various PET tracers were reviewed that can be used in the early diagnosis and differential diagnosis on AD in recent years.