Abstract: Objective To evaluate the immediate effectiveness and medial-term effectiveness of peer education on AIDS prevention among university students.Methods Experimental study was adopted.These 419 freshmen from a foreign language university in Beijing were class-based randomly divided into the experimental group and the control group.Peer education on AIDS prevention was implemented among the experimental group students.Results There was no significant difference between two groups before education.One week after the educaiton,the net increase rates of AIDS knowledge,safe-sex konwledge,self-efficacy of AIDS prevention,safe-sex intention were respectively 41.5%,18.8%,5.5% and 5.4% among male students in the experimental group,while 64.6%,78.9%,8.2% and 9.1% among female students.And persistent effectiveness formed among female students that the net increase rates of AIDS/safe-sex knowledge were still higher than 18% and those of safe-sex intention and self-efficacy were about 5%.Conclusion Peer education was suitable for foreign language university students and had good immediate and medial-term effectiveness.This kind of intervention method can be more widely carried out.