Objective: To explore the difference between bilevel positive airway pressure (BiPAP) and nasal continuous positive airway pressure (NCPAP) as respiratory support after extubation in infants underwent cardiac surgery. Methods: A retrospective analysis was performed on 83 infants who underwent repair of atrial septal defect (ASD) or ventricular septal defect (VSD) in our hospital from January 2020 to December 2020. According to ventilation mode, the patients were divided into BiPAP group (n=42) and NCPAP group (n=41). Blood gas index, PaO2/FiO2, non-invasive ventilation time, extubation failure rate, total enteral feeding time, and complications of the two groups were measured before the treatment and at 6 h, 12 h and 24 h after treatment. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05. Results: At 6 h, 12 h and 24 h after treatment, PaO2/FiO2 in BiPAP group was significantly higher than that in NCPAP group (P<0.05). At 12 h and 24 h after treatment, PaCO2 in BiPAP group was significantly lower than that in NCPAP group (P<0.05). There was no statistically significant differences in non-invasive ventilation time, extubation failure rate, total enteral feeding time, and complications between the two groups (P>0.05). Conclusion: Both BiPAP and NCPAP can be used to improve the ventilation of infants underwent repair of ASD or VSD, while BiPAP is more beneficial to improve oxygenation and correct carbon dioxide retention.