Abstract： Metastasis is the main cause of death in lung cancer patients,but there is a lack of ef-fective drugs for prevention and treatment of lung cancer metastasis currently.As the"seeds"of tumor metastasis,the number and phenotype dynamic changes of circulating tumor cells(CTCs)can reflect the occurrence and development of tumor metastasis in real time.This paper reviews the implication of CTCs in the metastasis of lung cancer,focusing on the detection of CTCs for metastasis risk assessment and clinical efficacy evaluation,and explores CTCs as a potential biomarker for prevention and treatment of lung cancer metastasis.