The pain at the connection between the nasal cavity and the mouth may be generally caused by acute nasopharyngitis, in addition, acute sinusitis can also cause this symptom, and reflux esophagitis can occasionally cause this symptom, it is generally recommended to go to the hospital in time for examination. 1. Acute nasopharyngitis: it may be a pain in the connection between the nasal cavity and the oral cavity, and at the same time there will be a foreign body sensation. It may also be accompanied by spitting of bloody pus sputum, and in severe cases, necrotic tissue may be spat out. 2. Acute sinusitis: it is usually accompanied by headache, pus and snot, and the nose is out of breath, which can occur when the pus irritates the nasopharynx. 3. Reflux esophagitis: the reflux of gastric acid will stimulate the nasopharynx, resulting in pain in the connection between the nasal cavity and the oral cavity, usually to a lesser extent. However, other factors can not be ruled out, it is recommended to consult a doctor in time to clarify the cause of the disease, and then give targeted treatment.