Tumor markers of small cell lung cancer mainly include neuron-specific enolase (NSE), with reference value ≤12.5µg/L, and gastrin-releasing peptide precursor (GRP), with reference value 2-50pg/mL. 1. Neuron-specific enolase (NSE), the positive rate of serum NSE detection in small cell lung cancer patients can be as high as 65%-100%, which is 5-10 times higher than that of other types of lung cancer and normal people, and it can be used as a tumor marker with high specificity and sensitivity for small cell lung cancer, and NSE is also a specific marker for neuroblastoma. 2. Gastrin-releasing peptide precursor (ProGRP), which mainly exists in gastrointestinal tract, respiratory tract and central nervous system, is a highly specific tumor marker for small cell lung cancer, with a reference value of 2-50pg/mL, and the specific value varies according to the different detection methods and instruments, and the likelihood of suggesting small cell lung cancer is as high as 93% when the serum ProGRP＞150ng/L. The combination of the two in the diagnosis of small cell lung cancer can significantly improve the accuracy. The diagnosis of small cell lung cancer needs to be combined with clinical manifestations, such as the patient’s symptoms, signs and symptoms, and other auxiliary examinations, such as CT, tissue puncture pathology, etc., in addition to the reference of tumor markers. It is suggested that patients should consult the doctor in time and should not be negligent to avoid delaying the condition.