Abstract: Common anterior mediastinal tumors include thymic tumors, germ cell tumors, and lymphomas. The clinical manifestations of anterior mediastinal tumors vary with tumor size, location, and benign and malignant. Early symptoms are atypical and lack specificity. Generally, some chest pain, hernia and other symptoms appear when the tumor is enlarged. Therefore, early diagnosis is difficult and it is easy to be misdiagnosed and missed. The author selected 2 cases of anterior mediastinum, analyzed the ¹⁸F-FDG PET/CT imaging features and clinical features for differential diagnosis, summarized the diagnosis ideas, and improved the diagnostic accuracy.