The detection of blood tumor markers in lung cancer patients helps in the diagnosis, prognosis and efficacy observation of lung cancer. Currently, the tumor markers commonly used in clinical practice for lung cancer are: i. Carcinoembryonic antigen (CEA) CEA is a fetal protein present in adult cancer tissues, and is a soluble glycoprotein with complex structure. It is synthesized in the small intestine, liver and pancreas during embryonic stage, and the serum level is extremely low in adults (generally <5mg/L.) CEA can show significant increase in serum level in patients with various malignancies. However, it has a low sensitivity and a low positive rate. Therefore, CEA is a broad-spectrum tumor marker, and although it cannot be used as a specific indicator for the diagnosis of lung cancer, it still has important clinical value in the differential diagnosis of lung cancer. Neuron-specific enolase (NSE) can be used to assist in the diagnosis and monitoring the therapeutic effect of small cell lung cancer. NSE concentration gradually decreases to normal when treatment is effective, and increases when recurrence occurs. Using NSE elevation to monitor recurrence is 4-12 weeks earlier than clinical determination of recurrence. It can also be used to monitor changes in neuroblastoma, evaluate the efficacy of treatment and predict recurrence. CyFRA21-1 is a new marker for lung squamous epithelial cell carcinoma and non-small cell lung cancer, and is significantly elevated in patients with lung squamous epithelial cell carcinoma with a sensitivity of 70% and specificity of 95%. It is important for the early diagnosis, efficacy observation and prognosis of non-small cell lung cancer. Squamous cell carcinoma antigen (SCC) SCC is a lung cancer tumor marker for squamous epithelial carcinoma, and it is a tumor marker for squamous carcinoma with good specificity. The positivity rate of squamous lung cancer is 46-90%, and the concentration of SCC in serum increases with the aggravation of the disease. However, its sensitivity is low, and it can be used as an auxiliary diagnostic index for lung cancer. V. Glycoantigen 125 (CA125) CA125 antigen is also present in benign and malignant exudate of lung cancer, and some patients with lung cancer have different degrees of elevated serum CA125. TPA is a non-specific tumor marker and a broad-spectrum tumor marker. For general tumor marker examination of lung cancer, single or multiple tests can be selected from several tumor markers such as CEA, CA125, NSE, SCC, CyFRA21-1, etc., especially if several indicators are combined, the effect is better.