Abstract: Objective To analyze the unprotected sexual behavior and condom use rate among sexually transmitted HIV-positive patients,imitating the effectiveness of improving condom access on preventing HIV transmission through sexual behaviors. Methods A survey was conducted among sexually transmitted HIV-positive patients using questionnaires to collect general information during the last 6 months before notification of HIV infection. Effectiveness of improving condom access on preventing HIV transmission was estimated by mathematical models. Results Among total subjects, the condom use rate was only 36.4%. During the last 6 months before notification of HIV infection, 63.6% never used condoms, 14.8% sometimes used, 9.6% often used, and only 12.0% insisted on using condoms. The reasons why subjects did not insist on using condoms were different, with 30.9% didn't obtain condoms timely when they had unprotected sexual behaviors. As expected, the occurrence of unprotected sexual behaviors and new cases of HIV infections were decreased by 13.79% and 10.92%, respectively, by improving the condom access. Conclusions Providing access to condoms in public places would reduce HIV transmission.