The problem of vaccination is very common in the course of daily treatment and really bothers many parents. It is recommended to grasp several principles: 1. Children with simple precocious heart disease can generally be vaccinated as planned; 2. Children with recurrent respiratory and digestive tract infections, feeding difficulties and weight gain should be alerted to combined immune deficiency, and children should be alerted when receiving attenuated vaccines, such as polio sugar pills, measles vaccine and BCG vaccine; 3. Children with precocious heart disease undergoing surgical treatment are recommended to start vaccination 3 months after surgery; 4. If fever, diarrhea, rash, etc. occur within 2 weeks before vaccination, the vaccination should be postponed to avoid confusion with normal vaccination reactions; 5. Contraindications to routine immunization include: (1) Immunodeficiency, malignant diseases (tumor, leukemia) and those whose immune function is suppressed by the application of radiation therapy or anti-metabolic drugs cannot use live vaccines; (2) Vaccination targets are suffering from fever or obvious general discomfort (2) Vaccination should be postponed for acute diseases; (3) Vaccination should not be continued for those who have had serious adverse reactions to previous vaccinations; (4) Children with neurological diseases, such as epilepsy and infantile spasms, should not be vaccinated with vaccines containing pertussis antigens.