Abstract: HIV infection increased rapidly in men having sex with men (MSM) in recent years, which was one of the reasons responsible for the more serious AIDS epidemic. No intervention can be effectively conducted among MSM at present due to the fact that they can not be found easily. As the wide use of Internet, more and more MSM tend to use Internet in seeking sex partners, which facilitates the increases of sex partner number and HIV related risk behavior among them. This review summaries the progress on the research of AIDS epidemiology in men having sex with men and seeking sex partners through Internet.