Abstract: Objective To understand the prevalence of syphilis among HIV positive men who have sex with men (MSM) in Liaoning and related factors. Methods Among HIV positive MSM visiting clinics of voluntary counsel and test for HIV(VCT) from 2011 to 2014 in Liaoning, those who were toluidine red untreated serum test (TRUST) and treponema pallidum particle assay (TPPA) positive were selected. Univariate logistic regression and multivariate logistic regression analyses were conducted by using the data of the cases collected from Comprehensive database for AIDS prevention and Control. Results A total of 1653 HIV positive MSM were reported from 2011 to 2014 in Liaoning, and 264 were both TRUST and TPPA positive, the prevalence of syphilis was 16.0%.Univariate analysis showed that age, marital status, history of STD and consultants source were factors affecting syphilis prevalence among HIV positive MSM. Multivariate analysis showed that divorced/widowed (OR=1.745), history of STD (OR=11.171), passive consultation (OR=1.618) were the risk factors for syphilis prevalence for HIV positive MSM. Conclusion The prevalence of syphilis in HIV positive MSM was relatively high, therefore, targeted prevention and control of syphilis/HIV co-infection should be conducted in MSM.