Oral submucous fibrosis (OSF) is a chronic, progressive and potentially malignant oral mucosal disease. Patients often have a habit of chewing betel nuts. Areca catechu has been listed as a Class 1 carcinogen by the International Agency for Research on Cancer (IARC), and its main active component, arecoline, is classified as a Group 2B carcinogen by the IARC. The World Health Organization (WHO) categorises OSF as an oral potentially malignant disorder (OPMD). The present guideline describes the risk factors, clinical symptoms and clinical signs of OSF. Clinical staging, auxiliary examination methods, basis for diagnosis and differential diagnosis and the need to improve bad lifestyle habits are proposed and addressed, and local treatment drugs, therapies, dosage and course of treatment, possible adverse reactions, and oral treatment drugs, dosage and course of treatment are proposed. The guideline also addresses the indications for surgical treatment, alternative non–drug treatment methods, selection of treatment plans for different clinical stages, criteria for efficacy evaluation, and preventive measures.