Oral precancerous lesions refer to oral mucosal lesions that are not clinically cancerous, but may be cancerous if they persist for a long time. The most common precancerous lesion is oral leukoplakia, which is a white lesion in the oral cavity that cannot be defined as other diseases, and the pathological manifestation is mainly epithelial hyperplasia and hyperkeratosis. It is a red lesion on the oral mucosa, which is a precancerous lesion of the oral cavity with a relatively high cancer rate. In addition, lichen planus and oral submucosal fibrosis are all precancerous lesions, among which many patients are related to betel nut chewing.