The prevention of infectious diseases must be carried out from three aspects: eliminating the source of infection, cutting off the route of transmission and protecting the susceptible herds. We must take comprehensive measures including four basic links: maintenance, prevention, inspection and treatment. The usual defensive measures: _( 1)_ Strengthen feeding management, do a good job in environmental sanitation and disinfection, and enhance the disease resistance of livestock. Carry out the principle of self-propagation and self-sample, and reduce the spread of epidemic diseases. _(2)_ Formulate and implement regular vaccination and replanting plans. _(3)_ Regularly kill insects and rodents, and conduct harmless treatment of feces. _(4)_ Seriously implement frontier quarantine, traffic quarantine, market quarantine and slaughter quarantine, and find and eliminate the source of infection in time. _(5)_ Veterinary epidemic prevention agencies in various places (provinces and cities) should investigate and study the distribution of local epidemic situations, organize neighboring areas to conduct joint defense and cooperation on livestock infectious diseases, control and eliminate specific epidemic situations in a planned way, and prevent the introduction of exotic diseases.