China currently has a vaccine for encephalitis B. It is an important way to prevent encephalitis B. At present, there are two types of vaccines, namely, live attenuated vaccine and inactivated vaccine. The most used vaccine in China is the live attenuated encephalitis B vaccine. The target of vaccination is children who were born at least eight months ago, and the first dose of vaccination is used as the basic immunization, and the second dose is used at the age of two years to strengthen the effect. Those who are allergic to any components of the vaccine, those who suffer from acute or chronic diseases, severe chronic diseases, those with immunodeficiency, and those with neurological diseases such as convulsions, encephalopathy and epilepsy are prohibited from receiving the vaccine. After vaccination, most children generally have no special reaction after vaccination. Individual children after injection may appear inoculation site mild redness, swelling and pain, low fever, skin rash, etc., generally in 2 ~ 3 days can be self-cured, if not self-cured, we recommend timely access to hospitals, under the guidance of the doctor targeted treatment.