Malignant pleural disease is a common clinical problem, and about 25% of elderly patients with pleural effusion are associated with primary malignant tumors of the pleura. Among malignant pleural diseases, primary tumors account for about 10%, such as pleural mesothelioma and pleural smooth muscle sarcoma, and secondary tumors account for about 90%, including: lung cancer, breast cancer, ovarian cancer, etc. Pathological diagnosis is still the gold standard for tumor diagnosis. Pleural cytology and pleural biopsy guided by CT or ultrasound are common clinical examination methods. Thoracoscopy provides clinicians with the opportunity to look directly into the pleural cavity and potentially diagnose and/or treat the lesion. Medical thoracoscopy (also known as pleuroscopy) is an invasive technique used to treat patients with pleural effusions that cannot be diagnosed by non-invasive methods. Internal thoracoscopy can observe changes in the chest cavity under direct vision and can perform biopsies of all layers of the pleura, which is of great practical importance for the diagnosis of pulmonary pleural diseases. Indications: ① pleural effusion whose etiology cannot be clarified by various non-invasive methods; ② staging of lung cancer or pleural mesothelioma; ③ talc pleural fixation for patients with malignant effusion or recurrent benign effusion; ④ local treatment of stage I and II spontaneous pneumothorax; ⑤ others include biopsy of diaphragm, mediastinum and pericardium, etc. At present, our department has introduced the latest Olympus internal thoracoscopy equipment, which has been carried out for the diagnosis and treatment of patients with pleural fluid that is difficult to diagnose by conventional pleural fluid examination and various solid tumors combined with refractory pleural fluid. This technique is simple, low cost, fast recovery, high diagnosis rate and obvious efficacy.