Smallpox virus is a highly infectious DNA virus. Smallpox virus has now been eradicated globally. Smallpox virus is the causative agent of human smallpox disease. It is a double-stranded DNA virus belonging to the family of poxviridae, which can tolerate dry and low-temperature environments and has a high viability, but does not tolerate humidity and heat. Smallpox virus mainly invades the human body through the mucous membrane of the respiratory tract, and is transmitted through droplet inhalation or direct contact. The incubation period after infection with smallpox virus is about 12 days (7-17 days) on average. Initial symptoms of infection include high fever, fatigue, headache, rapid heartbeat, and other flu-like symptoms. 2 to 3 days later, a typical smallpox rash will appear on the face, arms, and legs. In the early stages of the rash, there will also be a light reddish colored lumpy area that accompanies the rash. The disease is symptomatic, progresses rapidly, and can be life-threatening in severe cases. Smallpox is an infectious disease that has been a serious threat to human health both historically and globally, but has now been eradicated globally thanks to the development of the cowpox vaccine and widespread vaccination.