High neuron-specific enolase is mainly common in small cell lung cancer and neuroblastoma, and other related tumors are lung adenocarcinoma, large cell lung cancer and cancers of the nervous system. Patients with small cell lung cancer have significantly higher NSE levels than non-small cell lung cancer such as lung adenocarcinoma, lung squamous carcinoma, and large cell lung cancer, which can be used for differential diagnosis and monitoring the therapeutic effect of small cell lung cancer after radiotherapy and chemotherapy. When treatment is effective, NSE concentration gradually decreases to normal levels, and serum NSE increases when recurrence occurs. Monitoring recurrence of small cell lung cancer with neuron-specific enolase is 4-12 weeks earlier than clinical determination of recurrence weeks. The normal value of serum NSE level should be less than 16.3ng/ml, and now NSE has been used as one of the important markers of small cell lung cancer.