There is a strong fishy odor in the nasal cavity, which is divided into two cases for children and adults: 1. Children are first considered to have a foreign body in the nasal cavity, which needs to be removed if present.2. Adults need to be considered to have a sinusitis, which requires a sinus CT examination as well as an examination of the nasal cavity. If the diagnosis is confirmed, conservative treatment is feasible. Oral antibiotics, such as clarithromycin and trimethoprim nasal spray, can be taken. If the treatment is ineffective, surgery should be considered, and currently endoscopic sinus surgery is used. In addition, the postoperative period should be strengthened with dressing changes and nasal sprays, and follow-up is very important.