Background: Primary synovial sarcoma of lung is an extremely rare tumor. The etiology and pathogenesis of sarcomas lung are not well understood. A definitive diagnosis requires detailed connecting clinical symptoms, radiological imaging, immunohistochemical staining and may be molecular genetics techniques. Case Report: A male patient, 46 years old, history disease about 5 days with dry cough, dyspnea and right chest pain. Image manifestations: right pleural effusion and lung collapse. He had been taken the right pleural drainage and then the right lung surgery to remove the tumor. Right lung tumors are associated with right pleura, pericardium and mediastinal invasions. The diagnosis is confirmed with immunohistochemical staining of positive specific markers: PanCK, CD 5/6, CD99, Bcl-2, Calretinin, WT-1, Podoplanin Conclusions: Primary Pulmonary Synovial Sarcom is a mesenchymal malignant disease in the lungs, very rare. The disease progresses rapidly, involving the parenchyma of the lungs, pleura, or pericardium, the lymph nodes or nearby tissues. The diagnosis have determined by immunohistochemistry