Objective To investigate application values and techniques of robot-assisted extended thymectomy for the treatment of typeⅠmyasthenia gravis （MG） using Da Vinci S system. Methods We retrospectively analyzed clinical data of 3 patients with MG who underwent robot-assisted extended thymectomy in General Hospital of Shenyang Military Command from March 2012 to September 2012. All the patients were ocular MG （typeⅠ） including 2 men （33 years and 66 years old respectively） and 1 woman （21 years old）. Surgical outcomes were analyzed. Results All the 3 patients successfully received robot-assisted extended thymectomy without accessorial incisions. None of the patients required converting to open sternotomy or postoperative reexploration for bleeding. Intraoperative blood loss was 5-10 ml．Overall operation time was95-138 minutes, and thymoma dissection time was 26-80 minutes. No myasthenic crisis or other major postoperative complic-ation occurred. Postoperative chest drainage duration was 3-9 days and postoperative hospital stay was 10-15 days. Two patientswere followed up for 6-12 months after discharge without MG recurrence. Conclusion Robot-assisted extended thymectomy is safe and feasible for the treatment of typeⅠMG with satisfactory results．