Parents usually call phlegmolytic drugs should be called expectorant drugs, and there are several kinds of expectorants commonly used by children: 1.Aminobroxol oral solution: it is a mucolytic agent, which can make respiratory secretions less viscous; promote respiratory cilia movement; make phlegm easy to cough up. 2.Guaiacol glycerol ether: it can stimulate the gastric mucosa, reflexively cause the increase of airway secretion, reduce the viscosity, and have certain effect of diastolic bronchial. 3.Acetylcysteine: It can break the disulfide bond of mucin, reduce the viscosity of sputum, have a strong mucolytic effect, and make mucus sputum easy to cough up; besides oral granule form, acetylcysteine also has nebulized inhalation form, which can be put together with other nebulized inhalation drugs (inhaled hormone and inhaled bronchodilator) to play a comprehensive role of anti-inflammation, bronchodilatation and expectoration. 4. Ambrotero oral solution: It is a compound preparation (Ambroxol hydrochloride plus Clenbuterol hydrochloride), which can reduce the viscosity of respiratory secretions, while Clenbuterol hydrochloride has the effect of dilating bronchial tubes to relieve wheezing. In addition to this, there are many other cough and expectorant Chinese medicines that are usually chosen by doctors and parents to use. It is important to choose the expectorant medicine reasonably according to the specific condition and age characteristics of the child.