Oral cancer mainly refers to epithelial cancer occurring in oral mucosa, which is one of the more common malignant tumors of head and neck. Oral cancer accounts for about 2%-5% of the total incidence of cancer in the whole body, with fast progress, wide infiltration and poor prognosis. If we can grasp the warning signals of its early manifestation, achieve early diagnosis and early treatment, we can completely improve the cure rate and survival rate, which are called tongue cancer, buccal mucosa cancer, gum cancer, floor of mouth cancer and hard palate cancer, etc. because of the different parts of its occurrence. 1.Multiple unexplained bleeding in the mouth. 2.Persistent restriction of mouth opening that cannot be relieved. 3.Unexplained persistent tooth pain. 4.Rapid loosening and loss of teeth within a short period of time. 5.Unexplained bad odor in the mouth within a short period of time. 6.Unexplained white or red plaques in the oral mucosa. 7.Unexplained enlargement and pain of lymph nodes in the neck. 8, granular, cauliflower-like neoplasm or persistent ulceration and pain in the oral and maxillofacial region. 9.Unexplained pain and numbness in the tongue, cheeks, lips and other parts of the mouth. 10.Ulcers on the cheeks, tongue, and gums that have not healed in three to four weeks. 11.The local area of oral mucosa becomes hard, with raised and uneven edges. When the above signs appear in your oral cavity, it should cause you to pay great attention and go to a specialist hospital for further examination as early as possible.