This research adapts comprehensive qualitative and quantitative research methods to investigate HIV/AIDS related risks among male migrant workers at a highway construction site in western Yunnan.It is found that their major HIV/AIDS risk is related to high-risk commercial sex.Because of various reasons,a highly tolerant atmosphere towards commercial sex has been formed among migrant workers.They tend to under estimate the HIV/AIDS risks they are facing.Different occupational groups’ risk behaviors have been shaped by their differential knowledge level and social-economic contexts.Based on those findings,the authors discuss and advance recommendations for current HIV/AIDS prevention interventions among migrant workers,social perspective in HIV/AIDS prevention research,and directions for future research.