Abstract: Objective To explore related risk factors of syphilitic infection among men having sex with men(MSM).Methods Two hundred and sixty-one eligible homosexual men were recruited to participate in the study by using Driven Sampling(RDS)and informative key person's referral and internet advertising and direct contacts in gay bars in Hefei and Wuhu and Huainan1Of participants,twenty-two MSM were infected with syphilis.Case-control study based on result of test of syphilis was conducted.Ration of cases to controls was 1:4 depending on age and occupation.The participants were interviewed by face to face.Variables included social demographic characteristics,number of homosexual and heterosexual partners,sexual behaviours and venues of social activities and result of HIV-test.Results Lower awareness of HIV/STIs infection,multiple sexual partners,frequently participating in homosexual party,having casual sex partner,lower rate of condom use when having anal intercourse were risk factors of syphilis infection.Conclusion The risk behavioral intervention should be emphasized for increasing awareness of HIV/STIs infection and reducing number of sexual partners and promoting condom use.