To assess the value of B-ultrasonography in the diagnosis and treatment of emergency complications in lung cancer patients.Thirty-five patients with lung cancer who suffered from emergency conditions were examined with B-ultrasonography. Of the 35 cases, 5 had superior vena caval syndrome due to compression by a centrally located tumor mass in the right upper lobe; 10 had moderate to large accumulation of fluid in the pericardium with cardiac tamponade; 2 had metastasis to the myocardium and pericardium with acute hemorrhagic pericardial effusion; 20 had massive pleural effusion. The ultrasonographic features of these complications were described. Patients with pericardial or pleural effusion received intervention treatment with Elemen emulsion under B-ultrasound guidance.Combined with systemic chemotherapy, in 4-week period, complications were temporarily ameliorated in 82.8% and became clinically stable in 8.5% of the cases. Treatment was of no effect in 8.5%.B-ultrasonography is of value in the diagnosis of emergency complications of lung cancer and is of help to guide intervention treatment.