A constant odor inside the nose is a condition that, in the case of children, is highly clinically suspicious of the possibility of a nasal foreign body. In children, if a nasal foreign body is accidentally inserted into the nasal cavity for a long time, the foreign body will decay inside the nasal cavity and a foul odor may appear. Clinically, for this condition, it is recommended to do an electronic nasopharyngoscopy and other examinations to remove the foreign body using nasal endoscopy. In the case of adults with nasal odor, clinically most of them have chronic rhinosinusitis, which may be caused by the decaying infection of bacteria such as anaerobic bacteria inside the nasal cavity, leading to the possibility of nasal odor. Of course there are patients who have nasal lymphoma or nasal cancer infection and develop some odor. Some patients, if they have atrophic rhinitis, may also have bad odor due to the decay of protein scabs inside. All in all, if a patient has a foul odor in the nose, it is recommended to do a nasal endoscopy and, if necessary, to check the sinus CT and other examinations to avoid leakage and misdiagnosis of the disease.