Abstract: Objective The present study was designed to understand the status quo and trend of AIDS epidemic in Dali prefecture．Methods The data from AIDS/HIV serological surveillance in Dali prefecture in 2004 were analyzed．Results Serological surveillance was done on 13 961 high-risk population in Dali in 2004，of whom 1222 cases were found to be infected with AIDS/HIV．The HIV positive detection rate was 0.62％at the sentinel sites for pregnant women，11.65％ at the sentinel sites for drug abusers and 0.68％at the sentinel sites of STD clinics．77.09％of the victims were infected through blood transmission．18.49％through sexual transmission and 1.15％through mother-to-baby transmission．With the transmission route unknown in 3.27％of the infected．Young adults accounted for 85.92％of all the infected,with peasants and the unemployed predominantly involved in terms of occupation，constituting 44.76％and 36.99％ respectively．Conclusion In recent years，AIDS spreading has become wider and wider in Dali Prefecture，with blood transmission as a predominant route and sexual transmission increasing year by year．HIV infection Is found among unlicensed prostitutes in 12 counties/cities of the prefecture．HIV infection is increasing among pregnant women．The epidemic situation of HIV infection in Dali Prefecture must be taken seriously．