To children to grow cowpox is to prevent smallpox, smallpox once belonged to one of our country’s Class A infectious diseases, caused a pandemic in the world, highly contagious, can be transmitted through direct contact or respiratory tract, into the body after a large number of copies and spread to the blood, resulting in serious toxemia in humans, but after recovery can get lifelong immunity. The initial stages of smallpox may include sudden onset of high fever and head and back pain. The typical manifestation is a skin rash, mostly on the head, face and the ends of the limbs, which starts as a maculopapular or measles-like rash, then turns into a papule, then into a blister with a depression in the middle and a red halo around it, and finally transforms into a pustule, and is accompanied by a rise in body temperature and increased symptoms of toxicity. If the pustules are dry and crusted, itchy, and the body temperature drops, it means that it is in a state of general improvement, and usually the crusts fall off after 2-4 weeks, leaving a scar. Smallpox has no specific treatment drugs and has a high mortality rate, which can only be prevented by early vaccination against cowpox. Due to the discovery of the cowpox vaccine in the 18th century, smallpox has now been largely eradicated, and domestic vaccination against cowpox is no longer available.