Abstract: ObjectiveTo understand knowledge about HIV/AIDS and sexual behavior among men who have sex with men(MSM) in Miangyang City, and to analyze factors influencing HIV infection.MethodsFrom February to June in 2017, MSM were recruited by using snowball sampling method in Mianyang City, Sichuan Province to conduct anonymous questionnaire survey.Univariate and multivariate logistic regressions were used to analyze factors influencing HIV infection. ResultsA total of 400 MSM were investigated. The total awareness rate of HIV/AIDS knowledge was 97.0%, the coverage rate of intervention service was 88.8%, the rate of anal sex among MSM was 87.3% in recent 6 months, the rate of commercial sexual behavior was 2.0%, and the rate of heterosexual behavior was 14.5%. Of all the MSM, 89.6%(355/396) sought sexual partners by using the internet/dating software. The confirmed positive rate of HIV infection was 6.8%. Multivariate logistic regression showed that those with college or above education（OR=0.156）and those who received condom promotion and distribution/HIV counseling and testing in recent year（OR=0.286）had lower risk of HIV infection,while those with uncertain sexual orientation（OR=16.107）and those with unprotected anal sex behavior in recent 6 months（OR=2.832）had higher risk of HIV infection.ConclusionThe awareness rate of AIDS/HIV was high in Mianyang City in 2017. Those with low levels of education, uncertain sexual orientation, and unprotected anal sex had greater risk of HIV infection.