 Physiologic studies show higher nCPAP pressures improve lung mechanical properties. Though potential side effects have been of concern in practical application, there is no formal evidence supporting the concept that increased CPAP pressure results in a higher risk of complications. In relatively stable preterm infants, the range of optimal CPAP level needs to be established in order to adequately support the upper airway and lungs, without increasing complications secondary to the pressure applied. Given the uncertainty of the nCPAP pressure that should be used in very preterm infants, we conduct a randomized controlled trial to compare the effectiveness of two ranges of nCPAP pressure for post-extubation support in very preterm infants. 