Tetralogy of Fallot is the most common type of cyanotic congenital heart disease surgery, and its clinical manifestations depend mainly on the degree of right ventricular outflow tract obstruction. (1) Cyanosis is the most prominent symptom of the disease. Cyanosis is not obvious at birth and tends to become obvious with age, due to the progression of right ventricular funicular hypertrophy, by 6-12 months of age. (2) Shortness of breath and paroxysmal dyspnea are also among the common symptoms, mostly appearing after crying or exertion, and are more common in infants and children from 2 months to 2 years of age. (3) Children often have squatting phenomenon, which is manifested by walking a certain distance and then squatting, with both lower limbs flexed and both knees against the chest. (4) Severely ill children may have hypoxic attacks, manifested as pallor, weakness of limbs, paroxysmal syncope, is only convulsions and other symptoms, mostly in the early morning, after defecation or activity. Children with severe tetralogy of Fallot with hypoxic episodes should be operated early in infancy, and those with frequent episodes should be operated urgently. (5) The child is generally poorly developed, thin, with obvious cyanosis of the lips and mouth, cyanosis and pestle-like fingers (toes) at the end of the limbs due to hypoxia, and the severity of the pestle-like fingers (toes) is proportional to the degree of hypoxia. Children do not have the language to express their situation, but many symptoms can be observed by parents. Once the child is found to have abnormal performance, it is necessary to promptly seek medical attention.