Objective: To determine the protective effect of zero-balanced ultraifltration and modiifed ultraifltration on infants’ pulmonary function atfer cardiac surgery. Methods: Sixty infants with congenital heart diseases were randomly divided into 3 groups: a zero-balanced ultraifltration group (Z group), a modiifed ultraifltration group (M group) and a zero-balanced ultraifltrationwith modified ultrafiltration group (Z+M group). Oxygenation index (OI), difference of alveoli-arterial oxygen pressure (P(A-α)O2), static lung compliance (Cstat), and airway resistance (Raw) were measured before caridopulmonary bypass (CPB, T1), 20 minutes atfer the CPB (T2), 2 h atfer the operation (T3), 6 h atfer the operation (T4) and 12 h atfer the operation (T5). hTe time of mechanical ventilation was also monitored. Results:Atfer the CPB, OI and Cstat in all groups decreased signiifcantly, while Raw and P(A-α)O2 increased signiifcantly. At T3, T4 and T5, OI and Cstat in the Z+M group were signiifcantly higher than those in the Z group and the M group (P<0.05), Raw andP(A-α)O2 in the Z+M group were signiifcantly lower than those in the Z group and the M group (P<0.05). hTe ventilation time in the Z+M group was signiifcantly shorter than that in the Z group and the M group (P<0.05). Conclusion:Zero-balanced ultrafiltration and modified ultrafiltration can effectively promote the pulmonary function atfer cardiac surgery in infants.