Objective To compare the effects of extraluminal use of the Arndt endobronchial blocker and CO2 artificial pneumothorax for one lung ventilation in infants and children. Methods A total of 28 infants and children, aged from 6 to 36 months, American Society of Anesthesiologists (ASA) grades Ⅰ or Ⅱ, who were scheduled for thoracoscopy were selected. After induction of general anesthesia, they were placed with the Arndt endobronchial blocker or a single lumen tracheal tube, with one lung ventilation if needed during surgery. According to the differences in diseased lung collapse method, they were divided into two groups based on the random number table method (n=14): an Arndt endobronchial blocker group (group A) and a CO2 artificial pneumothorax group (group C). Then, we observed and recorded the changes of mean arterial pressure (MAP), heart rate, and airway pressure (Paw) before intubation (T1), after intubation (T2), when one lung ventilation began (T3), when one lung ventilation ends (T4), and at the time of extubation (T5), and blood analysis was performed at important time points during surgery to measure arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2). We also recorded lung collapse degree, one lung ventilation time, extubation time, as well as the condition of perioperative hypoxia (with less than 90% of SpO2). Results Operation was successfully finished in all patients. Compared with group C, group A presented remarkable increases in MAP at T2, T4 and T5 and Paw at T4 and T5 (P<0.05), as well as marked decreases in Paw at T3 (P<0.05). Group A also showed higher scores of lung collapse immediately and over 20 min than group C (P<0.05). No statistical differences were found as to heart rate, PaCO2, PaO2, one lung ventilation time and hypoxia incidence between the two groups (P>0.05). There was one case of hypoxia due to tube displacement in group A. Two children in group C presented hypoxia due to excessive chest pressure for a long time. No serious adverse outcomes were found. Conclusions Compared with CO2 artificial pneumothorax, extraluminal use of the Arndt endobronchial blocker has better effects on lung collapse at the diseased side and more stable hemodynamics in infants and children with one lung ventilation.