Abstract: Objective To provide scientific basis for making controlling measures related to AIDS by analyzing their perceived HIV risks and knowledge,the prevalence and facts for HIV/AIDS among male STI patients who experienced commercial sex behaviors.Methods A total of 258 male STI clients were enrolled in the cross sectional study.The standard surveillance questionnaire and HIV/STDs-tests were applied to all participants in the clinic of Yunnan province.Results 2%(2/100)particeipants were identified HIV positive.Factors associated with HIV risk were the instance of casual sex partners and the will of voluntary counseling testing(VCT).The proportion of the HIV/AIDS knowledge score(which was calculated based on answers to 21 quest ions)more than 12 was 65.5%;Factors associated with the HIV/AIDS knowledge score were education,age and occupation.Conclusion HIV and other STDs are highly prevalent among male STI clients.The HIV/AIDS related high risk behaviors were common,and the proportion of the VCT was low in this group people.HIV/AIDS in terventions should therefore be reinforced among the male STI patients,especially the farmer group.