The reason why AIDS can be prevented is that there is now a more detailed and accurate clinical understanding of how AIDS is transmitted. HIV is mainly found in the blood, semen, vaginal secretions, pleural and abdominal fluids, cerebrospinal fluid, and breast milk of people with AIDS, so the most common ways of transmission of AIDS are sexually transmitted, blood-borne, and mother-to-child transmission. For these modes of transmission, there have been some effective preventive measures, such as sexual transmission, patients must do to eliminate high-risk sexual behavior. For blood transmission, patients should not go to irregular medical institutions for invasive operations, and should go to regular medical institutions for abortion and tooth extraction to avoid drug abuse. For pregnant women who have been found to be infected with HIV, mother-to-child interruption of treatment must be carried out in a timely manner.