To evaluate the immediate effectiveness of peer education on AIDS prevention and provide bases for AIDS prevention education. Methods: A survey was conducted in October 2007 among 4 500 students from 15 colleges and universities in Nanjing on students’ knowledge, attitude and behavior concerning AIDS. A training program for AIDS prevention peer education was carried out among 1 400 college students of Grade 1 to Grade 3 selected by the methods of stratified cluster sampling in these colleges and universities. A parallel comparison group was then made about the effectiveness of the peer education, students receiving training as the intervention group and another 2 000 students not receiving training as the control group. Results: Comparing the proportions of knowing AIDS’s relative knowledge, having positive attitude to safe sex behavior and AIDS patients, the intervention group was significantly higher than pre-intervention group and parallel control group(P<0.05). The comparison between pre-intervention group and parallel control groups showed no statistical significances on several survey items(P>0.05). Conclusion: Peer education is suitable for university students and has good immediate effectiveness. The application and generalization of this effective means plays a highly important role in preventing and controlling the spread of AIDS.