Abstract: ObjectiveTo know the characteristics of men who have sex with men(MSM)in Haikou and the prevalence rate of HIV and syphilis infection among the MSM.MethodsA cross-sectional face-to-face questionnaire survey was conucted among MSM recruited with snow ball sampling in Haikou city,Hainan province.Blood samples were collected from the MSM for HIV and syphilis detection.ResultsTotally 248 MSM completed the questionnaire survey with 140 active participants(56.5%),85(34.3%)recruited through internet,and 97(39.1%)from other provinces.In the last six months,there were 221(89.1%)of the MSM having sex with men,44(17.7%)having sex with women,and 12 (4.8%)having commercial sex.HIV prevalence rate in the MSM was 2.0% and syphilis prevalence rate was 10.5%.The HIV prevalence rate of the local MSM and MSM from other provinces were 2.6% (4/151)and 1.0% (1/97),respectively (P>0.05).The HIV prevalence rate of MSM having sex with women was 4.5% (2/44)and that of syphilis was 9.1% (4/44).For the MSM at the age of less than 20,20-29,30-39,and above 40 years,the HIV prevalence rate were 4.3% (1/23),1.2% (2/268),2.3% (1/44),and 7.7% (1/13),respectively(P>0.05).ConclusionThe young MSM (<20years),elder MSM(>40years),MSM having commercial sex,and MSM having sex with women have higher prevalence rate of HIV and syphilis and they are the key intervention groups in AIDS prevention.