Objective: To explore the clinical characters, pathological, and prognostic distinctions between Thymoma patients with and without myasthenia gravis(MG). Methods: We undertook a retrospective study of patients treated for Thymoma at a single institution from 2008 to 2018. The patients were divided into two groups according to the presence or absence of MG. The surgical efficacy, pathological stage, and survival rate were compared and analyzed between patients with and without MG. Results:354 patients met our inclusion criteria. Patients were categorized into two groups based on whether they had MG. A total 301 patients in group without MG, including 139 males and 162 females, had an average age of 54.11±12.57 years, and an average tumor diameter of 6.42±2.94cm. In group without MG, there were 147 cases (48.8%) in Masaoka stage Ⅰ, 68 cases (22.6%) in stage Ⅱ, 15 cases (5.0%) in stage Ⅲ, 71 cases (23.6%) in stage Ⅳ. A total 53 patients in group with MG, including 31 males and 22 females, had an average age of 53.74±10.21 years, and an average tumor diameter of 53.74±10.21cm. In group with MG,there were 24 patients in Masaoka stage Ⅰ (45.3%), 16 patients in stage Ⅱ (30.1%), 4 patients in stage Ⅲ (7.6%), and 9 patients in stage Ⅳ (17%). There was no significant difference in Overall survival (OS) between two groups. Multivariate analysis suggested that age ≥55 years old, tumor diameter ≥6cm, postoperative pathological type B, Masaoka stage Ⅲ-Ⅳ, and the need for follow-up treatment were risk factors affecting the prognosis of thymoma patients. Conclusion:Patients with thymoma and MG are younger and have a smaller tumor diameter than those without MG. Complete resection is crucial for improving the prognosis of thymoma patients, while accurate postoperative pathological classification and staging can enhance prognostic prediction.