Oral cavity malignant tumors, mostly located in exposed areas, are characterized by short course, rapid progress and high malignancy. Oral cancer may have no obvious symptoms in early stage, so it is easy to be misdiagnosed as chronic inflammation, ulcer disease, dental disease or granulation tissue proliferation, etc. When the symptoms are obvious, the cancer is mostly in the middle and late stage, which brings difficulties to the radical treatment of tumor. Therefore, it is very important to recognize the early symptoms and pre-cancerous manifestations of oral cancer for tumor prevention and early diagnosis and treatment. Early symptoms of oral cancer mainly include: 1.Sudden loosening or loss of teeth, poor bite when chewing food, discomfort of dentures for those who have dentures, numbness and pain in the mouth and pharynx, and no improvement after general anti-inflammatory and symptomatic treatment. 2, the oral mucosa appears long-term unhealed ulcers, and the mucosa pale, lose luster, similar to white spots, fibrous cords under the mucosa occurs hard nodules. 3.The appearance of limited lip mucosa thickening or scaling, accompanied by gray-white keratinized spots. 4.The oral mucosa suddenly appears erythema, edema, erosion, white-spot chap, flat moss, bulge or granular granulation, although there is no obvious discomfort, but after treatment for 2-4 weeks instead of healing, but spread and increase. 5.Some bulges in the oral cavity are benign lesions, such as papilloma, denture stimulation-induced hyperplasia, septic granuloma, etc., but a few of them may evolve into squamous cell carcinoma, which should also be alerted. 6.Sudden appearance of restricted tongue movement, slurred speech, pain in the pharynx when speaking and swallowing. 7.Multiple unexplained bleeding in the oral cavity and difficulty in opening and closing the mouth. 8.Early symptoms of oral cancer include sudden increase of saliva secretion, bloody nose, choking sensation in swallowing, lumps and lymph nodes enlargement in the jaw and face, which persist and even gradually worsen.