Mediastinal tumors are divided into two categories: benign and malignant. Ninety-five percent of primary tumors and asymptomatic mediastinal tumors in adults are benign, 47% of symptomatic tumors are benign, and 25%-50% are malignant. The most common types of mediastinal tumors are neurogenic tumors, thymomas, and teratomas. Mediastinal tumor has no obvious symptoms in early stage, but the tumor can cause cough, shortness of breath and chest pain when it compresses the trachea; it can cause difficulty in swallowing when it compresses the esophagus, and it can cause superior vena cava compression syndrome when it compresses the superior vena cava. The tumor is more malignant if it grows faster. Thymoma has a certain relationship with myasthenia gravis. In addition to radiotherapy for malignant lymphogenic tumors, most primary mediastinal tumors should be treated surgically as long as there are no other contraindications. Even if there is no symptom, surgery is appropriate because it will gradually grow and compress the adjacent organs, and even malignant transformation or secondary infection will occur. If malignant mediastinal tumor has invaded adjacent organs and cannot be removed or has distant metastasis, surgery is contraindicated and radiotherapy or chemotherapy can be given according to the pathological nature. Our department has accumulated rich experience in mediastinal tumor resection and thymus surgery for myasthenia gravis, which has saved the lives of dozens of patients with malignant mediastinal tumor and myasthenia gravis. In addition, benign mediastinal tumors and myasthenia gravis can be treated thoracoscopically according to patients’ specific conditions.