Cough is one of the common symptoms of respiratory diseases in children, and chronic cough is defined as a cough lasting more than 4 weeks. Its clinical features are mainly: persistent or recurrent cough, which may be accompanied by itchy throat, clearing of the throat, nasal congestion and runny nose. The causes of chronic cough include upper airway cough syndrome, cough variant asthma (CVA), gastroesophageal reflux syndrome (GERS), infectious cough or post-infectious cough, psychogenic cough, and eosinophilic bronchitis (EB). It can be caused by a single etiology or by multiple etiologies, making it difficult to diagnose and treat. 1. Cough variant asthma (CVA): also known as allergic cough or cryptogenic cough, the clinical diagnosis is usually based on childhood asthma control routines. The main clinical manifestation is recurrent or prolonged cough, lacking typical asthma signs, mostly manifested as irritating dry cough, nocturnal cough, often at night and/or early in the morning, aggravated after exercise or transporting cold air or special odor stimulation. 2. Cough after respiratory infection: one of the main causes of chronic cough in children of different ages, this type of patient is extremely common in clinical practice. It may be due to non-specific inflammation of the airways caused by infection, with the loss of airway epithelium damage, exposure of subepithelial sensory nerves, mucosal congestion and edema, inflammatory cell infiltration and release of inflammatory mediators, which stimulate cough receptors. In addition to viral infections such as syncytial virus and adenovirus, there are increasing reports of chronic cough in children caused by Mycoplasma pneumoniae and Chlamydia, and airway hyperreactivity often develops after syncytial virus or Mycoplasma pneumoniae infection and persists for several months, resulting in recurrent and persistent cough and wheezing. This can be combined with relevant tests such as Mycoplasma pneumoniae antibodies. 3. Upper airway cough syndrome (UACS): It is a general term for various nasal, pharyngeal and laryngeal diseases that cause cough, previously called postnasal drip syndrome (PNDS), including allergic rhinitis, infectious rhinitis, vasomotor rhinitis and structural rhinitis, etc. Among them, allergic factors play an important role in causing chronic cough in children with sinusitis, and its typical clinical manifestations include postnasal drip, frequent throat clearing, pharyngeal mucus adherence and cobblestone-like signs. 4. Gastroesophageal reflux disease (GERD): The characteristic symptoms of GERD are heartburn and reflux, but they can also be manifested as belching, nausea, epigastric pain or retrosternal pain, etc. Its extraesophageal manifestations are chronic cough, asthma, and chronic laryngitis. Previous studies have suggested that cough symptoms mainly manifest as light day and heavy night and morning paroxysms followed by vomiting, but the current literature reports that cough mostly occurs during the day or in the upright position. The diagnosis needs to be further supported by barium meal of the gastrointestinal tract and 24h acid measurement, the latter being the current gold standard for the diagnosis of GRE cough. 5. Eosinophilic bronchitis (EB): The main manifestations are chronic dry cough or morning cough with little mucous sputum in children, EOS > 3% in adults and > 2.5% in children, negative acetylcholine excitation test, no evidence of reversible airway obstruction, and effective hormonal therapy. 6. Congenital airway disease and foreign body inhalation: Congenital airway disease is mostly symptomatic in the neonatal period and is associated with dyspnea, persistent or recurrent respiratory infections, in addition to chronic cough. Chest X-ray, lung CT or bronchoscopy can help in the diagnosis. Foreign body aspiration aspiration caused by dysregulated sucking and swallowing movements is a common respiratory disease in children, especially in infants and young children. 7. Other diseases: With the recent improvement of diagnostic techniques, tuberculosis and other findings can cause chronic cough in children, with clinical manifestations of cough as the main symptom, which may be accompanied by night sweats, flushing of the face and other symptoms, and need to be further combined with chest X-ray, PPD, sputum culture and other related examinations. Psychogenic cough has been reported to be seen in adolescent patients.