The following diseases are the main clinical causes of nose inability to smell and olfactory failure: first, chronic rhinitis and sinusitis induced. This may be caused by local mucosal swelling of the olfactory fissure or blockage of nasal secretions, resulting in air not reaching the olfactory area, thus causing the patient’s sense of smell to fail. This condition can be treated with nasal spray hormone and antihistamine nasal spray, oral mucus promoter, antibiotics, nasal rinse and other treatments to promote the reduction of nasal mucosal swelling and promote nasal ventilation to restore the sense of smell. Secondly, patients with nasal cavity growths may suffer from poor nasal ventilation, which may cause loss of sense of smell, such as nasal polyps and olfactory neuroblastoma. This condition should be treated clinically by surgery. After surgical removal, waiting for the nasal ventilation to be better, some patients will have some recovery of smell. Thirdly, some patients have cold or upper respiratory tract infection, which causes the virus in the nasal cavity to invade the olfactory nerve, resulting in degeneration and necrosis of the olfactory nerve. In this case, symptomatic treatment with nerve nourishing drugs can be used in the short term. If the onset of the disease is long, the clinical treatment effect may not be very good.