Alzheimer disease （AD） is a common form of elderly dementia that currently lacks effective treatment. Therefore， early diagnosis and intervention are particularly important. Currently， peripheral biomarkers are becoming a research hotspot in AD. Recent studies have shown that plasma p-tau217 plays an important role in the early diagnosis， differentiation， treatment monitoring， and prognosis evaluation of AD， and has good application prospects. However， further standardization of laboratory protocols and optimal cut-off values need to be determined. This paper reviews the above progress， aiming to provide a basis for clinical applications.