Swollen left supraclavicular lymph nodes are commonly caused by the following possibilities: first, tuberculosis infection, when suffering from tuberculosis, tuberculosis bacteria can follow the lymphatic channels to other parts of the lymph nodes, especially the supraclavicular and infraclavicular lymph nodes, so it is necessary to go to the hospital to check the chest X-ray, chest CT, spot test and tuberculin test, etc., if the disease requires active anti-flooding treatment. Second, lymph node metastasis of malignant tumors, such as lung cancer, stomach cancer, etc., need to check tumor markers, chest and abdomen CT, chest and abdomen MRI, and if necessary, need to perform lymph node puncture biopsy, remove lymph nodes for biopsy to clarify their nature. Thirdly, bacterial or viral infections can be clarified by routine blood tests and body ultrasound. In conclusion, if the lymph nodes continue to swell and do not subside, it is necessary to go to the hospital in time to clarify the cause.