The causes of submandibular lymph node enlargement are generally related to inflammation, tumor and environmental factors, as follows: 1. Inflammation: inflammation of the oral and maxillofacial region and the pharynx is the main cause, which is mostly caused by mixed bacterial or viral infection. In the acute stage, there may be redness, swelling, heat, pain and other characteristics of the local area, and the enlarged lymph nodes of individual patients may also be active. 2. Tumor: oral or facial tumors can invade submandibular lymph nodes and make them enlarged, such as nasopharyngeal cancer, oral cavity cancer, laryngeal cancer, etc. 3. Environment: if staying in dry, dusty or smoky environment for a long time, it may cause acute pharyngitis, which will affect submandibular lymph nodes and lead to enlargement. It is recommended to consult a doctor for timely treatment of enlarged submandibular lymph nodes under the guidance of a doctor.