Myocarditis, an inflammatory lesion of the heart muscle, can occur in children of all ages and often follows infections of the respiratory and intestinal tracts. Children show signs of heart damage a few days to 2 weeks after infection. 1.Prodromal infection symptoms: such as fever, vomiting and diarrhea, sore throat, rash; the prodromal period may be without cardiac symptoms. 2.Non-specific symptoms: poor mental health, fatigue, loss of appetite, and reduced activity. 3, cardiac symptoms: nausea, vomiting, abdominal pain, pallor, weakness in young children. Older children may complain of precordial discomfort, palpitations, dizziness, abdominal pain, and myalgia. 4, more serious symptoms: the child refuses to eat, pale, vomiting, dyspnea, dry cough. 5.Severe heart failure manifestations: dyspnea, sitting breathing (can’t lie flat), irritability, cyanosis, cyanotic limbs, chills. Myocarditis is an inflammatory lesion of the myocardium, with a wide range of clinical manifestations, from asymptomatic in mild cases to fulminant cardiogenic shock or acute congestive heart failure in very severe cases, resulting in death or sudden death within a few hours or days. Myocarditis can occur in the acute or recovery phase of viral infection, and the acute infection is easily masked by other symptoms of infection, especially in those with mild symptoms, which cannot be detected, and without timely treatment there will be a convention to become cardiomyopathy.