Nasopharyngeal cancer refers to malignant tumors occurring in the nasopharynx, which is one of the common malignant tumors in China, with Guangdong, Guangxi, Fujian and Hunan as the most frequent areas in China, especially in Guangdong Province, where the annual incidence rate is as high as (30-80)/100,000 people, so nasopharyngeal cancer is also called “Guangdong cancer”. The main clinical manifestations of nasopharyngeal carcinoma are: 1. Retractable aspirated snot and blood: it is manifested as blood in sputum after nasal aspiration or blood in snot when blowing nose, and in early stage there is only a small amount of blood in sputum or snot, which is sometimes absent. In the late stage, there may be nosebleed if there is more bleeding; 2.Tinnitus, hearing loss, occlusion in the ear and otitis media; 3.Headache; 4. Diplopia; 5.Facial numbness: numbness of facial skin; 6.Nasal congestion: nasal congestion may occur when the tumor blocks the posterior nostril, which is lighter when the tumor is small, and increases as the tumor grows, mostly unilateral; if the tumor blocks the posterior nostril bilaterally, bilateral nasal congestion may occur; 7.Lymph node metastasis in the neck Symptoms: nasopharyngeal cancer is prone to cervical lymph nodes; 8. tongue muscle atrophy and tongue extension deviation; 9. eyelid drooping and eye fixation; 10. distant metastasis, common metastasis sites are bone, lung, liver and other organs, simultaneous metastasis is common; 11. concomitant dermatomyositis. Nasopharyngeal cancer is sensitive to radiotherapy, and radiotherapy is the recognized preferred and effective treatment for nasopharyngeal cancer. Because of the deep location of nasopharynx and complex surrounding tissues, surgical treatment is ineffective and prone to recurrence. Conventional radiotherapy uses facial and cervical fields including nasopharyngeal cavity, skull base parapharyngeal space and cervical lymph node drainage area, which can effectively control the tumor with radical radiotherapy dose, but due to the large radiation area, the normal tissues in the radiation field will form radiation damage and have different degrees of recent and long-term radiation complications. Intensity-modulated radiotherapy is the abbreviation of three-dimensional conformal intensity-modulated radiotherapy, which belongs to the category of precision radiotherapy and is a new technology of radiotherapy developed and matured in recent years, which can increase the local control rate of tumor and reduce the radiation damage to normal tissues. The main advantages of intensity-modulated radiation therapy applied to nasopharyngeal cancer are: 1. One of the main advantages of intensity-modulated radiotherapy is to minimize the amount of surrounding normal tissues without reducing the local control rate of nasopharyngeal cancer patients. 3. Quality assurance and quality control are easier to achieve due to better body fixation of the head and neck, making nasopharyngeal cancer one of the best indications for the application of intensity-modulated radiotherapy.