There is a lymph node under the right jaw, the causes are mainly acute infection, malignant tumor, reactive hyperplasia and so on. 1. Acute infection: such as acute pharyngitis, oral ulcers, gingivitis, etc. will cause the phenomenon of right submandibular lymph node enlargement. 2. Malignant tumors: such as oral or nasopharyngeal malignant tumors, which will cause tumor cells to invade into the submandibular lymph node along the lymphatic vessels, resulting in enlargement and hyperplasia. 3. Reactive hyperplasia: such as necrotizing hyperplastic lymphadenopathy, allergic septicemia, systemic lupus erythematosus rheumatoid disease, Langerhans histiocytosis, lipid deposition disease, nodular disease and so on. Right submandibular lymph nodes may also be other causes, it is recommended to go to the hospital in time to do relevant examinations, to clarify the cause of the disease, follow the doctor’s instructions for treatment, do not delay the treatment time.