INTRODUCTION: The HIV prevalence among men who have sex with men (MSM) is increasing sharply in China. Many MSM have female sexual partners, representing a bridge of transmitting HIV to the general population. Circumcision reduces the risk of HIV prevention via heterosexual intercourse. AIM: The study investigated the prevalence and factors related to willingness to undergo circumcision when MSM were informed that circumcision could reduce risk of heterosexual HIV transmission. METHODS: An anonymous cross-sectional survey was conducted in Jiangsu, China. A total of 157 MSM with bisexual behaviors in the last six months were recruited using snowball sampling. MAIN OUTCOME MEASURES: Self-reported circumcision status and foreskin conditions were recorded. HIV-related knowledge, risk perceptions, risky sexual behaviors, cognitive and behavioral intention factors regarding circumcision were assessed. RESULTS: Among all respondents, 5.7% were circumcised. In the uncircumcised subsample, the willingness to be circumcised increased from 8.1% to 35.1% after they were informed about the 50% risk reduction effect of circumcision regarding heterosexual HIV transmission. Risk behaviors, uncertainty about the prevalence of HIV among MSM, perception of overly long foreskin, peer's suggestion, disagreement with the statements "MSM in general are not willing to be circumcised" and "circumcisions are for children, not for adults" and self-efficacy for circumcision were significantly associated with willingness for circumcision given the hypothetical risk reduction effect (OR = 2.37 and 3.11, respectively, P < 0.05). Perception of overly long foreskin, self-efficacy, and having used a condom in the last episode of sex with a woman remained significantly associated with the conditional willingness for circumcision in the multivariate analysis (OR = 3.03, 2.84 and 2.42, respectively, P < 0.05). CONCLUSIONS: Interventions promoting circumcision among bisexual MSM, based on the risk reduction effect on heterosexual HIV transmission, are likely to be successful. Such programs should focus on increasing self-efficacy and may consider utilizing a peer educator approach.