A 7-month-old male infant was diagnosed with Tetralogy of Fallot (TOF) shortly after birth. He was admitted to our hospital due to aggravated cyanosis after crying recently. He was scheduled to undergo TOF corrective surgery under general anesthesia. Children with TOF often have significant hypoxemia and cardiopulmonary dysfunction due to the obstruction of the right ventricular outflow tract and intracardiac right-to-left shunting, which reduces pulmonary blood flow. The right ventricular outflow tract spasm can also cause a sharp decrease in pulmonary blood flow and Tet spells, which can be life-threatening in severe cases. During the perioperative period, attention should be paid to managing systemic pulmonary vascular resistance to avoid further reduction of pulmonary blood flow. Proactive prevention and treatment of Tet spells should be conducted. After cardiopulmonary bypass, normal right heart and coagulation functions should be maintained.