Enlarged mediastinal lymph nodes of lung cancer are usually found to be more than 1cm, and the diagnosis is confirmed through mediastinoscopy to take pathological examination. Enlargement of mediastinal lymph nodes in lung cancer patients may be caused by metastasis of cancer cells or inflammatory changes caused by inflammatory reaction in lung cancer patients. Patients are considered to have enlarged mediastinal lymph nodes when they find mediastinal lymph nodes more than 1cm after chest X-ray, chest CT, etc. If the enlargement is inflammatory in nature, its boundaries are usually clearer and blood flow is not abundant, while if it is caused by metastasis of cancer cells, it is usually unclear in boundaries, irregular in morphology, and with richer blood flow. To identify which nature of enlargement and determine its stage, lymph node biopsy can be performed through mediastinoscopy. Patients are advised to consult a specialized doctor and under the doctor’s guidance to carry out the appropriate examination.