Abstract: Objective To understand the cognition of HIV/AIDS-related knowledge and high risk behaviors among urban residents in Gaozhou City. Methods Multistage sampling method was adopted to investigate the HIV/AIDS related knowledge, behaviors, and attitude among urban residents in Gaozhou. Data were analyzed by using descriptive epidemiology method. Results A total of 1 050 urban residents were investigated and 1 048 valid questionnaires were recovered, including 704 men and 344 women. Their average age was 31 years. The overall awareness rate of HIV/AIDS related knowledge was 61.45% (9 660/15 720 questions). The awareness rates were 19.5% (204/1 048) for sharing tableware with AIDS patients and 21.0% (220/1 048) for sharing toilets and bathroom supplies. Among the respondents, 93.5%（979/1 048）had sexual contact; 5.6% (55/979) had commercial sex behavior in the past year; only 6.1%（60/979) often used condoms; 67.6%（662/979) have never used condoms; 16.8%（176/1 048） thought HIV/AIDS prevention and control was closely related with themselves; 16.8%（176/1 048） thought that it was necessary to understand HIV/AIDS related knowledge; 3.8%（40/1 048）thought that only the immoral persons would get HIV/AIDS; 57.2%（599/1 048）thought that the HIV-infected persons and patients with AIDS should be isolated from healthy people. The residents with high educational level,females, and high family economic income had higher awareness of HIV/AIDS related knowledge （P<0.01 for all）. Conclusion The cognition degree of HIV/AIDS related knowledge is low among the urban residents in Gaozhou. The existing high-risk behavior still cannot be ignored. The propaganda of HIV/AIDS prevention knowledge and high-risk behavior intervention should be further strengthened.