Superior vena caval syndrome (SVCS) is a group of syndromes caused by partial or complete interruption of blood flow back to the right atrium through the superior vena cava, and is the most common clinical emergency in oncology. Patients present with acute or subacute dyspnea and swelling of the face and neck. Examination may reveal obstruction of venous return, bruising, and edema in the neck, upper extremities, and chest. Further development may lead to hypoxia and increased intracranial pressure, requiring urgent management to relieve symptoms. The mechanisms of obstruction are none other than the following: i.e. thrombosis, fibrosis, foreign compression and tumor invasion. Malignant tumors account for 78% – 86% of the various causes, of which 65% are lung cancer, 8% are malignant lymphoma, 12% are non-tumors, and 5% are unknown.