Oral cancer is often confused with the following two diseases: 1. Traumatic ulcer: It most often occurs on the lateral edge of the tongue, and there are always residual roots, sharp tooth tips, or unsuitable dentures opposite to the ulcer, indicating that the ulcer is caused by the above-mentioned irritants. However, the clinical examination of the ulcer is soft and the ulcer can heal on its own after 1 to 2 weeks of eliminating the irritant. 2, tuberculous ulcers: Most of them are the result of direct spread of open tuberculosis, often occurring in the soft palate, buccal mucosa and the back of the tongue, with shallower ulcers than cancerous ulcers, softer bases, no infiltrating hard nodules, and effective anti-tuberculosis treatment. Imaging and tissue biopsy can be performed to confirm the diagnosis.