Objective:To summarize the best evidence for preventing and managing radiotherapy-induced oral mucositis in patients with head and neck cancer.Methods:The clinical decisions, best practices, guidelines, expert consensus, systematic reviews, and evidence summaries regarding the prevention and management of radiotherapy-induced oral mucositis in patients with head and neck cancer were retrieved from UpToDate, British Medical Journal (BMJ) Best Practice, Agency for Healthcare Research and Quality, Medlive, National Comprehensive Cancer Network, European Society for Medical Oncology, Cochrane Library, Joanna Briggs Institute (JBI) Evidence-Based Health Care Center Database, PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang Data, China Biology Medicine disc and so on. The search period was from database establishment to November 30, 2023.Results:A total of 18 articles were included, involving six guidelines, two expert consensus, eight systematic reviews, and two evidence summaries. Thirty-four best pieces of evidence were summarized from six aspects of assessment: drug prevention, non-drug prevention, anti-infection and analgesic management, health education, and multidisciplinary team management.Conclusions:This study summarizes the best evidence for preventing and managing radiotherapy-induced oral mucositis in patients with head and neck cancer. Medical and nursing staff should consider the patient's characteristics, disease condition, and willingness when selecting and applying evidence.