Objective·To explore the effect of intracardiac shunts direction on preoperative cerebral tissue oxygenation in children with congenital heart disease. Methods·Sixty children aged from 4 to 24 months diagnosed with ventricular septal defect (VSD group), tetralogy of Fallot (TOF group) and indirect inguinal hernia (control group) undergoing elective surgeries were recruited, with 20 cases in each group. The NIRS cerebral oximeter was used to monitor TOI of patients. Two sensors were placed on the subject's forehead bilaterally for continuous monitoring of cerebral oximetry. Pulse oxygen saturation (SpO2), noninvasive blood pressure, heart rate were also measured and recorded. TOI and fractional tissue oxygen extraction (FTOE) were compared among the three groups and multiple linear regression analysis was used to evaluate the relationship between TOI and these parameters. Results·There was no significant difference in TOI between VSD group and control group (P>0.05). Both sides of TOI in TOF group were significantly lower than those in other two groups (P=0.000) and FTOE in TOF group were significantly higher than those in VSD group (P=0.005). Multiple linear regression analysis showed that only SpO2 was related to TOI in children with congenital heart disease (r=0.560, P=0.000). Conclusion·Different intracardiac shunts direction can affect cerebral tissue oxygenation through affecting systemic oxygen supply. Children with right-to-left shunt physiology have lower TOI and higher FTOE due to low systemic oxygenation.