If the baby cries at night after vaccination, it is mostly considered to be caused by vaccine reaction after vaccination, such as low fever, local redness, swelling and heat pain, etc. It may also be caused by fright during vaccination. 1. Excessive fright: If the baby cries at night after vaccination but has no other physical discomfort, such as low fever, loss of appetite, etc., it is mostly considered to be caused by fear after vaccination. It is recommended that parents soothe the baby more, such as stroking the baby’s back, humming songs, etc., to provide the child with a sense of security and relieve crying; 2. Adverse vaccine reactions: vaccination is a foreign stimulus to the human body, and local and systemic reactions of varying degrees will occur after vaccination, with systemic reactions mostly manifested as fever and local reactions including inflammatory reactions at the vaccination site, such as slight redness, swelling, heat and pain. Mild vaccine reactions will generally return to normal after 1-3 days. After the vaccination, parents should take the child’s temperature, closely observe the temperature and crying, let the baby rest more, drink water regularly, pay attention to a light diet, and pay attention to the hygiene of the needle eye to avoid infection; if the baby continues to cry and the vaccine reaction is not relieved, it is recommended to take the baby to the hospital for treatment according to the specific situation, and take physical cooling or use acetaminophen if fever occurs.