Viral hepatitis is a group of infectious diseases caused by many different hepatitis viruses, mainly liver damage, including hepatitis A caused by hepatitis A virus (HAV), hepatitis B caused by hepatitis B virus (HBV), hepatitis C caused by hepatitis C virus (HCV), hepatitis D caused by hepatitis D virus (HDV), and hepatitis E caused by hepatitis E virus (HEV). In recent years, some new types of viruses that may cause hepatitis have also been discovered. According to the statistics of “2001 national statutory infectious disease morbidity and mortality”, the incidence rate of viral hepatitis in China was 65.15/100,000 and the mortality rate was 0.06/100,000, which were the highest among all kinds of infectious diseases. As a contagious disease, each type of viral hepatitis has its own mode of transmission and preventive measures: 1, hepatitis A: HAV mainly through contaminated hands, water, food and eating utensils, such as oral infection, generally by daily contact as the main mode of transmission, most of the hidden infection. Prevention of hepatitis A focuses on good water and fecal management, diet and personal hygiene. For the epidemic season and high-risk groups, hepatitis A vaccination is available for specific prevention. 2, hepatitis B: HBV transmission is more complex, can be transmitted through blood, semen, menstruation and vaginal secretions, etc. The following three main transmission routes: perinatal mother-to-child transmission, blood transfusion and medical transmission, as well as sexual transmission and close contact transmission. For the prevention of hepatitis B, comprehensive preventive measures, mainly hepatitis B vaccination, are currently adopted and are effective. For HBsAg-positive pregnant women and their newborns, accidentally infected people, hepatitis B immunoglobulin can be given for vaccination. 3, hepatitis C: HCV is mainly transmitted through blood and blood products, followed by injecting drug users and unclean injections, sexual transmission, perinatal transmission, and medical transmission occur less frequently. The main measures for prevention are to strengthen the management of blood donors and blood products, reduce blood transfusions and the use of blood products, and prevent injection drug addiction and medical transmission. A vaccine for hepatitis C is under development. The main route of transmission is also blood transfusion and application of blood products, daily contact is also possible, perinatal transmission is rare. HDV is a defective virus that requires the assistance of hepatophilic DNA viruses (such as HBV) to be infectious, so people who have never been infected with hepatitis B will not be infected with HDV alone. the focus of prevention is to prevent HBV infection, vaccination against hepatitis B is the main measure, followed by the prevention of HBsAg-positive people should be prevented from re-infecting with HDV: minimize blood transfusion and use of blood products. Hepatitis D vaccine has not been successfully developed. 5, hepatitis E: mainly seen in developing countries, the majority of epidemics are water-based epidemics, mostly occurring in the rainy season and after the flood season, daily contact transmission is the second risk factor after water-based transmission. The disease has a high mortality rate in the elderly and pregnant women. Prevention is basically the same as for hepatitis A, with emphasis on water and fecal management, food hygiene and personal hygiene. A vaccine for hepatitis E is not yet available for clinical use. 6, GB virus C (GBV-C), TT virus (TTV) and SEN virus (SENV) may also cause viral hepatitis, its transmission route needs further study, its prevention is basically the same as hepatitis C.