Abstract: ObjectiveTo understand the epidemiological characteristics of HIV/AIDS cases in floating population in Ningbo, Zhejiang province during 2013–2017 and provide evidence for the prevention and control of HIV infection.MethodsThe epidemiological characteristics of HIV/AIDS cases in floating population were analyzed by descriptive epidemiologic method by using the reporting AIDS epidemic data in Ningbo during 2013–2017.ResultsIn recent 5 years, a total of 3 034 HIV/AIDS cases were reported, in which 22.45% left Ningbo; and 2 642 HIV/AIDS cases lived in Ningbo, in which 11.05% were from other areas. Most HIV/AIDS cases in floating population were young adults and unmarried. Most HIV/AIDS cases who came from other areas and left for other areas were not local residents. The education level of HIV/AIDS cases who left for other areas were concentrated in junior high school and below, the main transmission mode was heterosexual contact. The education level of HIV/AIDS cases who came from other areas were concentrated in junior high school and higher, the main transmission mode was homosexual contact. The anti-retroviral therapy rate was low among HIV/AIDS cases who left Ningbo (P＜0.05). The anti-retroviral therapy rate was high among HIV/AIDS cases who came to Ningbo (P＞0.05). The anti-retroviral therapy rate was low among death cases of HIV/AIDS. If receiving no anti-retroviral therapy, the difference in interval between the case reporting and death was significant between out-floating cases and in-floating cases (P＜0.05), the difference in death cause was no significant between out-floating cases and in-floating cases (P＞0.05).ConclusionThe proportion of HIV/AIDS cases in floating population was high in Ningbo, but the anti-retroviral therapy rate in out-floating cases was low, posing a greater risk of transmission as the source of infection. It is suggested to strengthen the follow up and anti-retroviral therapy in both our-floating cases and in-floating cases of HIV/AIDS to reduce the secondary transmission.