Abstract: Objective To understand the characteristics of heterosexual behaviors in men who have sex with men (MSM) in Guangzhou and related factors, provide scientific evidence for the development of AIDS/STD prevention strategies. Methods From April to August 2011, the questionnaire survey and voluntary counseling/testing were conducted twice a week among MSM in Guangzhou. Results Among 507 MSM surveyed, 17.8% (90/507) had sex with women in the past six months, in which 23.3% had 2 sex partners. Only 40.0% of MSM used condoms at each heterosexual activity. Multivariate logistic regression analysis indicated that marital status, erotism and the first sex partner were influential factors of MSM to have sex with females in past six months. The HIV and syphilis infection rates were 6.7% (6/90) and 5.6% (5/90) respectively among the MSM surveyed. Conclusion The prevalence of heterosexual behavior was high and condom use rate was low among the MSM in Guangzhou. It is necessary to strengthen the behavioral intervention and promote condom use in this population to prevent the spread of AIDS/STD to females.