AIDS sentinel surveillance is a series of cross-sectional survey methods, selecting representative areas and populations, in accordance with a unified monitoring program and testing reagents, continuously carrying out fixed-point, timed, quantitative HIV antibody testing, and at the same time collecting information on high-risk behaviors of the monitoring population related to the spread of AIDS, to obtain information on the status of HIV infection in different areas and populations, as well as the behavioral risk factors and trends of change. The information is available in different regions and populations.