The possible causes of bilateral submandibular lymph node enlargement are: infectious inflammation in neighboring areas, cervical lymph node tuberculosis, lymph node metastasis of malignant tumors, lymphoma and so on. 1. Inflammation: the spread of infectious inflammation in neighboring areas can stimulate the submandibular lymph nodes to reactive hyperplasia and enlargement, such as gingivitis, oral mucositis, tonsillitis, upper respiratory tract infections, etc. can cause bilateral submandibular lymph node enlargement. 2. Cervical lymph node tuberculosis: Mycobacterium tuberculosis can invade the lymph nodes and cause enlargement. Cervical lymph node tuberculosis is mostly caused by Mycobacterium tuberculosis invading through the oral cavity or tonsils, and it can also be secondary to pulmonary tuberculosis. 3. Lymph node metastasis of malignant tumors: malignant tumors of head and neck can occur submandibular lymph node metastasis and cause lymph node enlargement, for example, thyroid cancer, squamous cancer of head and neck, oral cancer, nasopharyngeal carcinoma and so on. 4. Lymphoma: Lymphoma is a malignant tumor originated from lymphatic tissues, and most of them take the swelling of lymph nodes on the body surface as the first symptom, especially Hodgkin’s lymphoma which occurs in cervical lymph nodes. Patients mostly present with painless progressive enlargement of lymph nodes without obvious reasons. If bilateral submandibular lymph nodes are found to be enlarged, it is recommended that the patient should go to the hospital as soon as possible to find out the cause and then be treated accordingly.