Abstract Objective To investigate awareness of STD / AIDS related knowledge and attitudes towards sexual behavior among college students in Nanjing, so as to provide scientific evidence for the health education of STD / AIDS prevention of in colleges. Methods Using a stratified random survey, 600 college students in four universities in Nanjing were enrolled to complete an anonymous self-administered questionnaire. Results The overall awareness rate of STD / AIDS related knowledge was respectively 21.4% and 55.3%. The awareness of AIDS related knowledge was better than that of STD. Difference of STD knowledge awareness rate among college students was statistically significant ( = 52.682, p <0.01).Difference of AIDS knowledge awareness rate among college students was also statistically significant ( = 36.357, p <0.001). Conclusion Awareness of STD/ AIDS related knowledge among college students is not optimistic, STD/ AIDS knowledge awareness is affected by many factors.