Lung cancer is the most common malignant tumor globally, with the highest incidence as well as mortality in China. Absence of the effective screening method for early detection results in the high mortality. Five-year survival rate in patients with advanced cancer decreases remarkably compared with that in patients with early stage disease. Hence, the early detection of lung cancer is of vital importance. DNA methylation has close correlation with the initiation and development of tumor genesis. With the improvement in DNA methylation, aberrant DNA methylation has been identified in lung cancer. Detection of methylation in the specimens, such as tissue, bronchoalveolar lavage fluid, serum or plasma, sputum and urine, contributes to the early detection and improvement in the prognosis and treatment of lung cancer.