Mucus hypersecretion refers to the secretion of mucus in excess of the normal amount, and mucus glands are generally referred to as mucus-secreting exocrine glands. They are composed of one or more mucus cells, as opposed to plasma glands. They are widely distributed in plants and animals, and in higher animals they are found in the mouth, nasal cavity, trachea, esophagus, stomach, intestines, excretory organs, etc. They are involved in the formation of mucus. Differential diagnosis of mucus hypersecretion: 1. Rhinitis is an inflammation of the mucous membrane of the nasal cavity, manifested as congestion or edema, and patients often have symptoms such as nasal congestion, clear watery mucus, nasal itching, throat discomfort, and cough. Smear examination of nasal secretions: during the onset of metaplasia, eosinophilic leukocytes are seen in the nasal secretions, and more eosinophilic leukocytes or mast cells can also be detected. 2, bronchiectasis Most often seen in children or young adults, the onset is often secondary to measles pneumonia or pertussis, and there is a history of coughing and sputum, recurrent episodes, increased sputum when combined with infection, and purulent or accompanied by fever, the course of the disease is often repeated hemoptysis, in the lower part of the lungs can often be heard around the easily dissipated wet? The sound is often heard around the lower part of the lungs. Patients with advanced severe disease often have pestle-like fingers (toes), and the texture of the lower lung fields is coarse or curly on chest radiographs. 3.Chronic interstitial lung fibrosis presents with chronic cough, coughing up a small amount of mucous non-purulent sputum, progressive dyspnea, crackles can be heard at the base of both lungs, and in severe cases, cyanosis and pestle-like fingers are present. Chest radiograph shows increased texture and disorganized reticular structure in the middle and lower lung fields and peripheral parts of the lungs, with diffuse fine spot shadows in between, and pulmonary function tests show restrictive ventilation dysfunction, reduced diffusion function and decreased PaO2.