Plastic bronchitis is identified by the presence of branching mucoid bronchial casts that obstruct airways. It is an uncommon condition, which was more described in lung disease and post-surgery congenital heart disease. We reported a case of a 26-month-old boy born at 29+6 weeks who presented with cough, wheezing and respiratory distress secondary to atelectasis of the left lung. After admission, the patient was treated with intravenous injection of azithromycin and methylprednisolone, inhaled bronchodilators, inhaled budesonide with short-acting beta-agonists and inhaled nebulized N-acetylcysteine. Dramatically, the patient expelled large casts, shaping as the tracheobronchial tree after a severe cough just on the night before the bronchoscopy. In toddlers who were born preterm with recurrent wheezing, the discharge of airway mucus secretion is altered, and the possibility of bronchial plastics needs to be alert.