Abstract: Tuberculosis can occur in multiple organs throughout the body. It's difficult to identify tuberculosis and other systemic diseases (especially tumor diseases) because of the different imaging features. ¹⁸F-FDG PET/CT has certain advantages in the diagnosis of systemic diseases, but it still needs to be analyzed in combination with clinical manifestations, laboratory tests, CT signs of lesions and concentration of ¹⁸F-FDG. The author select three cases misdiagnosed in clinical practice, namely intestinal tuberculosis, lung tuberculosis and bone tuberculosis, and analyze the clinical features and ¹⁸F-FDG PET/CT imaging features, and comb the diagnosis ideas in order to help with clinical diagnosis.