Abstract: Objective To investigate the effects of submandibular gland contouring on dry mouth and quality of life after three-dimensional intensity modulated radiation therapy (IMRT) in patients with nasopharyngeal carcinoma. Methods Total 72 patients with nasopharyngeal carcinoma who underwent radiotherapy in our hospital from April, 2015 to April, 2017 were randomly divided into the control group (36 cases) and the experimental group (36 cases). The control group received conventional IMRT, while the experimental group received IMRT on the basis of contouring the submandibular gland and limiting the dose of the submandibular gland. The average dose of the submandibular gland (D _mean), the volume of the submandibular gland after radiotherapy, the classification of dry mouth symptoms and the amount of saliva secretion and quality of life after radiotherapy were compared. Results The D _mean of the two groups was significantly higher than that of the healthy side (P<0.05). The volume of the submandibular gland in the control group was significantly lower than that of the healthy side after radiotherapy (P<0.05). The D _mean of the healthy side and the affected side of the experimental group were significant. The volume of the submandibular gland was significantly higher than that of the control group (P<0.05). The grade of dry mouth symptoms in the experimental group was significantly lower than that of the control group (P<0.05). The basis and stimulation of saliva secretion in the experimental group were significantly higher than those in the control group (P<0.05). The quality of life and total scores in the experimental group were significantly higher than those in the control group (P<0.05). Conclusion The submandibular gland contouring in three-dimensional IMRT for nasopharyngeal carcinoma can reduce the dose of submandibular gland in patients with submandibular gland, increase the amount of saliva secretion and reduce the degree of dry mouth after radiotherapy, and significantly improve the quality of life of patients.