Lung cancer can not be detected by blood test, but it helps in the diagnosis of lung cancer, and the definitive diagnosis requires imaging and pathology examination, so it is recommended to consult a specialist. Lung cancer hematology mainly refers to tumor markers, mainly carcinoembryonic antigen, neuron-specific enolase, cytokeratin 19 fragment, gastrin-releasing peptide precursor and squamous epithelial cell carcinoma antigen. Multiple tumor markers can be combined to improve the specificity and sensitivity of the test. However, tumor markers cannot be relied upon to definitively diagnose lung cancer. The diagnosis of lung cancer needs to be confirmed with the help of imaging methods, such as MRI, X-ray chest film, ultrasound, CT, nuclear imaging, PET, etc. If necessary, bronchoscopy and ultrasonic bronchocentesis biopsy can be performed to make a clear diagnosis. If lung cancer is suspected, it is necessary to use the correct method of examination to confirm the diagnosis and timely diagnosis and treatment.