Abstract: Objective To study the subtypes and transmission of human immunodeficiency virus type 1(HIV-1) predominant epidemic strains in Shenzhen city,and to provide reference for studying the prevalent trend of HIV-1.Methods Epidemiological investigation was carried out and 429 RNA fragments of HIV-1 env gene were amplified with nested reverse transcription polymerase chain reaction(RT-PCR).After gene sequencing,HIV-1 subtypes were differentiated.Phylogenetic analysis was performed based on the nucleotide sequence data.Results Sequence analyses showed that there were 01-AE,07-BC,08-BC,02-AG,B and C subtypes in Shenzhen.01-AE was the predominant subtype(51.8%).The major transmission routes included homosexual and heterosexual route,and intravenous drug using.Sexual transmission route was the main infection route(90.8%).Heterosexual virus had the highest inner group genetic divergence(14.3%) and the genetic divergence between heterosexual viruses and homosexual viruses was high(15.8%).In the evolutionary tree,viruses from various transmission routes formed relatively independent clusters,but there were also crosses.Conclusion 01-AE is the predominant HIV-1 strains in Shenzhen and sexual transmission route is the main infection route.