Objective: To investigate the sexual behaviors and acquired immunodeficiency syndrome (AIDS) knowledge acquisition of male students with human immunodeficiency virus(HIV)/AIDS before diagnosis, so as to provide reference for formulating policies and measures for AIDS prevention and control among young students. Methods: Qualitative interviews were conducted among 25 newly reported HIV/AIDS male students recruited from January 2021 to December 2023 in the district of Chengdu. The contents of the interviews included highrisk behaviors related to HIV infection, access to knowledge and psychological status after infection. Results: All interviewees had sex with men, and the mean age of first homosexual behavior was (17.48±1.64) years old. The time from first sexual behavior to confirmation ranged 0-8 years, with an average of (2.72±1.41) years. The proportion of condom use among interviewees was low, only 2 students reported using every time, and 12 students had never been tested for HIV infection before diagnosis. All interviewees were aware of knowledge about AIDS, but their awareness of risk was low. Among them, 16 thought that they would not be infected, 8 were aware of risks but held a luck mindset, and one did not know the role of such knowledge. Schools and Internet were the main ways to obtain knowledge. Among them, 3 got knowledge through Weibo, Douyin, Zhihu, etc., 9 got knowledge through school lectures, theme class meetings, etc., and 13 got knowledge through schools and the Internet. None of the interviewees had acquired AIDS related knowledge from family education. After knowing being infected, 21 students reported depression, frustration, pessimism, despair and other negative emotions(7 students expressed anxiety and depression, 9 students had fear and terror, 5 students felt regret) and only 4 students had a relatively calm attitude. Conclusions The primary reasons for the infection of young students are early age of first sexual behavior, multiple sexual partners, popularity of online dating and separation of AIDS knowledge and practice among HIV/AIDS male students. Targeted prevention and control measures should be developed to suppress AIDS transmission among young students.