Objective: Determine the serum level N-terminal pro-brain natriuretic peptide (NT-proBNP) of children with congenital heart disease after peri-cardiopulmonary bypass operation, and explore the relationship between NTproBNP level and prognosis.Methods: 22 subjects undergoing repair of congenital heart disease were studied.The serum level of NT-proBNP was measured by radioimmunoassay at the time of before, end, 4, 12 and 24 hours after CPB.Result: NT-proBNP levels increased after CPB and reached a peak at 12 hours after CPB.The duration of CPB and ACC was related to 4-hour post-CPB serum NT-proBNP levels, and mechanical ventilation (MV) duration related to each time point of post-CPB serum NT-proBNP level.12-hour NT-proBNP level was an independent predictor of the duration of MV.Serum level of NT-proBNP more than 19720.7 pg/ml can predict MV beyond 48 hours, with a sensitivity of 100.0% and a specificity of 84.2%.4 and 12 hour post-CPB NT-proBNP level were useful to evaluate the state of low cardiac output after surgical intervention, and NT-proBNP level more than 3954.7 pg/ml can predict low cardiac output state with a sensitivity of 100.0%, and a specificity of 70.6%.Conclusion: The serum level of NTproBNP during CBP is a useful clue to better manage complications of congenital heart defect operation and prevent organs impairment due to oxygen deficit.