Abstract: Lung cancer has become one of the malignant tumors with fastest growing morbidity and highest mortality in the world. Altered expression of microRNAs(miRNAs) in blood and sputum could reflect the development of lung cancer. Therefore, the miRNAs in blood or sputum could be used as new tumor biomarkers and applied to the early screening and diagnosis of lung cancer. This article reviews the roles of miRNAs in the development of lung cancer, and the clinical value of miRNAs in blood and sputum for the early screening and diagnosis of lung cancer.