Pox is also called smallpox. Smallpox is a virulent infectious disease caused by the smallpox virus, and is the first infectious disease to be eradicated by humans worldwide so far. Smallpox is caused by infection with the pox virus, and there is no cure for it. Smallpox virus is brick-shaped, about 200 nm x 300 nm, resistant to dryness and low temperatures, and can survive for months to a year and a half on scabs, dust and clothing. Anyone who has not been vaccinated against cowpox and has been exposed to smallpox patients and has developed the disease within 10 to 14 days can all be considered for this disease, which can be diagnosed if a typical rash appears again. According to the morphology of the rash, distribution and development process and other characteristics, combined with the epidemiological disease situation, the diagnosis of typical cases is not difficult. The diagnosis of difficult cases depends on the viral and serum immunological examination. The total number of leukocytes in the prodromal phase is slightly low and the number of lymphocytes is relatively high. In the pustular phase, the total number of leukocytes and neutrophils increase. 2.Serological examination Complement binding test, erythrocyte agglutination inhibition test and neutralization test can be used to detect the presence of specific antibodies in the patient’s serum to help diagnosis. 3, pathogenic examination (1) direct smear examination: take herpes fluid, or swab from the bottom of the herpes ulcer and apply it on a slide, dry it and stain it with hematoxylin-eosin (H-E) and observe the cytoplasm of epithelial cells under a light microscope. In case of smallpox patients, smallpox virus eosinophilic inclusion bodies can be found therein. However, a negative smear cannot exclude smallpox. (2) Electron microscopy: taken from the lesion and observed by electron microscopy, smallpox virus is brick-shaped, and the diagnosis can be confirmed within a few hours. (3) chicken embryo inoculation or cell culture: take herpes fluid, scab suspension, blood or nasopharyngeal secretions, inoculated in the chicken embryo chorionic allantoic membrane to isolate the virus; or inoculation of monkey kidney cells or amniotic cells for culture, 12h after the majority of tiny inclusion body can be seen, 48h after the inclusion body significantly increased, sometimes visible in the nuclear inclusion body.