Alzheimer's disease （AD） is a neurodegenerative disease that cannot be cured until now. The main existing diagnostic methods are the detection of biomarkers in cerebrospinal fluid and positron emission tomography （PET）， but their application in clinical practice is hampered due to the invasiveness and high cost of their testing. Biomarkers in blood samples can make early detection and diagnosis of ad universal because of their easy availability and low price. This article summarizes several common biomarkers of AD and their changes in AD patients， and prospects the development of ad biomarkers in the future.