To identify related factors associated with unprotected anal intercourse (UAI) among HIV-positive men who have sex with men (MSM) in the context of knowing their HIV infection status. HIV positive MSM who known that they had been infected with HIV for more than 6 months and accepted follow up services were recruited by convenience sampling method in Chengdu 2015. Semi-structured questionnaire was used to collect their information, such as demographic characteristics, antiviral therapy and sexual behavior characteristics . Logistic regression model was used for univariate and multivariate analyses. A total of 330 HIV- positive MSM were recruited, 201 eligible MSM were interviewed. The prevalence of UAI in recent six months was 18.41 (37/201). The results of multivariate logistic regression analysis revealed that the number of anal intercourse with male ≥3 in last month (=6.22, 95: 1.88-20.56), low education level (=7.29, 95: 1.36-39.16), married, divorced or widowed status (=4.65, 95: 1.13-19.17), homosexual cohabitation (=3.32, 95: 1.01-10.95) were the risk factors related with UAI among the HIV-positive MSM. Frequent homosexual anal intercourse, low education level, married, divorced or widowed status and homosexual cohabitation might be the risk factors related with UAI in HIV-positive MSM in Chengdu.