Common causes of hoarseness in infants are crying, acute laryngitis, vocal polyps, etc., which are analyzed as follows: 1. Crying: the infant’s respiratory mucosa is delicate, if the crying time is longer, it can cause redness and swelling of the vocal cords, resulting in the phenomenon of hoarseness of the infant’s voice. 2. Acute laryngitis: mainly caused by bacterial or viral infections, because the infant’s laryngeal cavity is narrow, cartilage is soft, the airway support ability is poor, easy to cause airway collapse, manifested as barking cough, hoarseness, and severe respiratory distress and suffocation. 3. Vocal cord polyps: infants with vocal cord polyps can appear when crying voice fatigue and weakness, pitch change, severe hoarseness and even breathing difficulties. The cause of infant hoarseness may also have other reasons, it is recommended to go to the hospital in time for relevant examinations, clear causes of the disease and actively treat the symptoms.