After surgery, radiotherapy is the second most important tool in cancer treatment. About 70% of tumor patients need radiotherapy in the treatment process. For early stage head and neck cancer such as laryngeal cancer, oral cavity cancer, oropharyngeal cancer, hypopharyngeal cancer etc., radiotherapy alone can achieve the same effect as radical surgery. For most patients with middle and advanced head and neck cancer, radiotherapy combined with surgery (such as preoperative radiotherapy and postoperative radiotherapy) or combined with chemotherapy and molecular targeted therapy can significantly reduce the chance of local recurrence and distant metastasis, prolong life and improve survival rate. In addition, because the anatomical structure of head and neck is very complex, tumors are usually adjacent to important organs, and radical surgical treatment often inevitably results in the loss of normal organ function. Controlling the tumor through radiotherapy, while preserving the integrity of the patient’s tissue and organ anatomy, greatly improves the patient’s quality of life.