Nasopharyngeal carcinoma is the most common head and neck malignant tumor in China. Due to the special anatomical location and biological characteristics of nasopharyngeal carcinoma, radiation therapy is the main treatment for nasopharyngeal carcinoma, with radical radiotherapy alone for early cases and chemotherapy combined with radiotherapy for locally advanced cases. Although the traditional two-dimensional radiotherapy technique can achieve good efficacy, the complications of radiotherapy, represented by dry mouth, seriously affect the quality of life of long-term surviving patients. The intensity modulated radiation therapy (IMRT) technique can significantly increase the dose to the tumor target area and decrease the dose to the normal organs surrounding the tumor, thus improving the local control rate of the tumor and reducing the complications of radiation therapy. This technique was pioneered in the United States in the late 1990s and introduced to China in the early 21st century. IMRT is most suitable for nasopharyngeal carcinoma, which requires that the tumor target area and normal organs to be irradiated should be outlined on the CT image first, and the target area should include not only the visible tumor volume (GTV) but also the subclinical target volume (CTV) before designing the 3D radiotherapy plan. The target volume is directly related to the therapeutic effect and toxic response of the tumor. Shang Fang Hui Zhen invited me to give a lecture on precise radiotherapy target area outline for nasopharyngeal carcinoma, and then put it on QQ to let more medical colleagues and interested netizens know about radiotherapy for nasopharyngeal carcinoma.