The main modes of transmission of AIDS include sexual contact, mother-to-child transmission and blood transmission. 1. Sexual contact: Sexual contact is the main mode of transmission, which includes high-risk homosexual, bisexual and heterosexual contact without condoms. Because HIV exists in vaginal secretions and semen and other body fluids, high-risk sex can lead to HIV transmission. 2. Mother-to-child transmission: HIV is also found in blood, amniotic fluid, breast milk and other body fluids, and can be transmitted through intrauterine infections, the passage of the fetus through the vagina during delivery, and breastfeeding. 3. Blood transmission: HIV can be transmitted through the bloodstream by tattooing, injecting drugs, or interventional medical treatment. To sum up, it is recommended to pay more attention in the course of life to minimize the possibility of HIV infection.