Cross-infection in the clinic usually refers to the mutual infection between patients and other people in the medical unit, and the main ways of cross-infection in the hospital are air, droplet, injection, infusion and so on. Cross-infection often occurs in hospitals, and is closely related to the disinfection and isolation system of hospital wards, ward management system, etc. Hepatitis B, influenza, acute gastroenteritis, bacillary dysentery and other diseases are prone to cross-infection. Medical institutions should try to avoid the occurrence of hospital cross-infection. To cause cross-infection, it is necessary to have the three links of infectious agents, transmission routes and susceptible groups. Prevention of cross-infection can be achieved by isolating patients and avoiding close contact with them. The environment in which the patient lives should be disinfected in time, such as cleaning the bathroom and toilet, using disinfectant to disinfect the floor and closet and other surfaces, to reduce the breeding of pathogenic bacteria, and dealing with the patient’s vomit, excreta and secretions in a timely manner; and at the same time, we should do a good job of personal protection, such as wearing masks and washing hands frequently.