At present, methods used in clinical screening of lung cancer,including detection of serological markers, imaging technology, and biopsy ,have some limitations:in the absence of imaging evidence, the serological assessment could not be used as the evidence for diagnosis and treatment strategy alteration for lung cancer. The application of low-dose computed tomography scan for lung cancer screening shows a high false-positive rate, which is liable to require excessive medical treatment. Biopsy does greater harm to patients with lung cancer; sampling is difficult, and effective information may be missed because of tumor heterogeneity. With the development of molecular pathology in cancer research in recent years, liquid biopsy has become an important developmental direction for clinical tumor detection because of its noninvasiveness, convenient sampling, and potential for overcoming tumor heterogeneity.Liquid biopsies include the detection of circulating tumor cells (CTCs), tumor exosome (exosome), circulating tumor RNA (ctRNA), and circulating tumor DNA (ctDNA) in peripheral blood.