Abstract: Objective To determine the epidemiologic characteristics of AIDS in Haiyan and identify its epidemic factors. Methods Descriptive epidemiological analysis was conducted based on the currently available monitoring data. Results Since the first case of HIV infection in 2000, a total of 20 patients had been found in Haiyan county by the end of December 2009, consisting of 9 local residents and 11 migrant workers. The major affected group was 20 to 40-year-old young adults. Eighteen cases were sexually transmitted. Conclusion Massive floating population, sexual openness and lack of prevention knowledge constituted the main causes of AIDS prevalence in Haiyan county. The trend of transmission was shifting from extra-marital to intra-marital relations, middle-aged groups to youngsters, transfusion to sexual activities, outsiders to local residents, and high-risk groups to general population.