Abstract: Objective To explore influencing factors of HIV/AIDS-related knowledge and behavior among male clients of STD clinics in Dongguan and analyze risk factors so as to provide the evidence for intervention. Methods HIV surveillance data from 2010 to 2012 among male clients of STD clinics in Dongguan were collected and analyzed. Content of the investigation contained demographic data, HIV/AIDS related knowledge, extramarital sex, drug use behavior, homosexual sex, and STDs. Venous blood samples were taken to detect antibodies of HIV and treponema (TP). Results A total of 1 200 male clients of STD clinics were surveyed. The HIV/AIDS related knowledge awareness rate was 48.42%（581/1 200). In the past three months, 31.75%（381/1 200）of the survey participants admitted extramarital sex. Men who had injecting drug use behavior and homosexual sex accounted for 1.00%（12/1 200） and 0.33%（4/1 200） of the all clients, respectively. Positive rates of antibodies of HIV and TP were 0.58%（7/1 200）and 8.25%（99/1 200）, respectively. The awareness rate of HIV/AIDS-related knowledge was significantly associated with age (OR=0.761), household register（OR=2.090）, ethnicity（OR=4.378）, and STD within last year（OR=2.010）. The sexual acts with non-spouse partners were correlated with the STD within last year (OR=7.208) and the aware of the HIV-related knowledge (OR=1.906). Conclusion The awareness rate of HIV/AIDS related knowledge was low among male clients of STD clinics in Dongguan and unsafe sex is still common.