The incubation period of AIDS is on average about 9 years. The length of the incubation period is related to the number of HIV infections and the immune status of the individual. Generally speaking, after HIV has invaded the human body, it mainly invades the immune system, resulting in a gradual decline of CD4 cells, which causes a series of opportunistic infections and tumors. The onset of AIDS is often due to opportunistic infections. Therefore, if there is an opportunistic infection, it is necessary to be alert to the possibility of AIDS.