Surgerys used in thymectomy for myasthenia gravis and anterior mediastinal tumours have become much less invasive in recent years. In our study, the surgical technique which resected the thymus below the xiphoid process and the technique which was regarded as conventional video- assisted thoracoscopic surgery (VATS) thymectomy was compared.

Inclusion Criteria:

1. Thymoma with or without myasthenia gravis；
2. Generalized myasthenia gravis not sensitive to conservative medicine treatment;
3. Good cardiopulmonary function.

Exclusion Criteria:

1. Cardiopulmonary function can't bear surgery;
2. Generalized myasthenia gravis with MuSK(+).