To investigate the risk factors of postoperative neuro-developmental abnormalities in neonates with critical congenital heart disease (CCHD). Clinical data of 50 neonates with CCHD admitted in the Cardiac Intensive Care Unit, The Children's Hospital, Zhejiang University School of Medicine from November 2020 to December 2021 were retrospectively analyzed. Neurological assessment was performed with cranial ultrasonography, CT/MRI, video electroencephalogram and clinical symptoms before and after surgical treatment for all patients, and neurodevelopmental abnormalities were documented. Binary logistic stepwise regression was used to analyze risk factors of postoperative new-onset neurodysplasia in children with CCHD, and the predictive value of the risk factors on postoperative neurodevelopmental abnormalities were evaluated using the receiver operating characteristic (ROC) curve. Neurodevelopmental abnormalities were detected in 22 cases (44.0%) and not detected in 28 cases (56.0%) before surgery. There were no significant differences in gender, birth weight, age at admission, gestational age, preoperative SpO2 level, prematurity, cyanotic congenital heart disease, and ventilator support between the two groups (all P>0.05). After surgery, there were 22 cases (44.0%) with new-onset neurological abnormalities and 28 cases (56.0%) without new-onset abnormalities. Multivariate logistic regression analysis showed that postoperative 24 h peak lactic acid (OR=1.537, 95%CI: 1.170-2.018, P<0.01) and postoperative length of ICU stay (OR=1.172, 95%CI:1.031-1.333, P<0.05) were independent risk factors for postoperative new-onset neurodevelopmental abnormalities. The area under ROC curve (AUC) of the postoperative 24 h peak lactic acid for predicting the new-onset neurological abnormalities after operation was 0.829, with cut-off value of 4.95 mmol/L. The diagnostic sensitivity and specificity were 90.0% and 64.3%, respectively. The AUC of postoperative length of ICU stay for predicting the new-onset neurological abnormalities after operation was 0.712, with cut-off value of 18.0 d. The diagnostic sensitivity and specificity were 50.0% and 96.4%, respectively. The AUC of the combination of the two indicators was 0.917, the diagnostic sensitivity and specificity were 95.5% and 64.3%, respectively. The incidence of neurodysplasia in neonatal CCHD is high, and new neurological abnormalities may occur after surgery. The postoperative 24 h peak lactic acid and postoperative length of ICU stay are risk factors for new-onset neurodysplasia after surgery. The combination of the two indicators has good predictive value for neurodevelopmental outcomes after surgery in CCHD infants.