Abstract: AIM To evaluate the time dependent effect of pulmonary surfactant (PS) in the treatment of acute postoperative respiratory distress syndrome (ARDS) in infants with congenital heart disease. METHODS Forty-three infants with congenital heart disease and acute respiratory distress syndrome after operation were treated with intratracheal PS. Their age, weight, surgery, cardiopulmonary bypass time, aortic clamping time, mechanical ventilation time, ICU time, fatality and complication rate were recorded. Their respiratory function indexes were recorded before administration and at 2 h, 6 h, 12 h and 24 h after administration, and the value of oxygenation fraction (PF), the oxygenation index (OI) and the ventilation index (VI) were calculated. RESULTS The average age of the studied children were (5.3±2.8) months, the average weight was (6.4±1.6) kg, the time of cardiopulmonary bypass was (151±23) min, and the aortic clamping time was (56±12) min. The average time of ICU treatment was (12±3) d after operation and the time of ventilator assistance was (194±26) d. One death occurred and postoperative complications occurred in 9 cases. After the application of PS, the respiratory index improved significantly and PaO₂ increased from 2 h to 24 h. The improvement was most obvious at 6h time point. The peak pressure, mean pressure and oxygen concentration of ventilator FiO₂(%) decreased gradually within 24 h after administration and changed significantly at 6 h time point. PF gradually increased in 24 h and the ventilation index VI and oxygenation index OI decreased gradually in 24 h. CONCLUSION PS is effective in the treatment of ARDS in infants with congenital heart disease and the infants' respiratory function in 24h has a time-related improvement.