Abstract: Patients with thymoma without preoperative myasthenia gravis may develop symptoms of myasthenia gravis after tumor resection. A comprehensive understanding toward this rare clinical phenomenon is lacking. Recent studies indicate that post-operatively new onset myasthenia gravis (ponoMG) is the result of multiple mechanisms and their interactions, which may be related to the thymoma-mediated production, release and long-term presence of abnormal T cells and autoimmune antibodies in the periphery, as well as the presence of ectopic thymus and late recurrence of thymoma. Preoperative antibody titer is the main predictor. The treatment strategy is based on anticholinesterase drugs and hormonal therapy. In this study, we review the incidence, pathogenesis, predictors, and prevention and treatment strategies of ponoMG.