Objective:This study aimed to discover the HIV infection and associated factors among male sex workers (MSW) who provide sexual services for men. Data from this study thus can be used to provide evidence for designing related intervention programs.Methods:In this observational study, MSW were recruited from May to July, 2019 in KTV venues in Wuxi, China. A questionnaire was used to collect information with blood sample collected and tested for HIV and syphilis. EpiData 3.0 and SPSS 17.0 software were used to clean up data and statistical analysis.Results:A number of 500 MSW were involved including 243 (48.6 %) heterosexual and 257 (51.4 %) homosexual MSW. The overall HIV prevalence was 5.4 %(27/500) among all the MSW. there were significant differences between the HIV prevalence rates, the heterosexual MSW (3.3 %, 8/243) and the homosexual MSW (7.4 %, 19/257)( χ2=4.112, P=0.043). In the past 3 months, 28.0 % (72/257) of the homosexual MSW mainly engaged in receptive anal sex which was higher than 11.5 %(28/243) of the heterosexual MSW. Compared to 15.6 % (40/257) of the homosexual MSW who engaged in heterosexual behavior, a higher proportion of 98.4 % (239/243) was noticed among the heterosexual MSW. Higher percentage (44.9 %, 109/243) appeared among the heterosexual MSW who had not been tested for HIV than the homosexual MSW (20.6 %, 53/257). Results from logistic regression multivariate analysis showed that age ≥30 (a OR=7.54, 95 %CI: 2.53-37.11), having unprotected anal sexual practice (a OR=3.76, 95 %CI:1.15-12.23), having anal sex after drinking alcohol (a OR=10.91, 95 %CI: 2.29-51.87) and syphilis tested positive (a OR=8.23, 95 %CI:1.29-52.51) were risk factors associated with HIV infection among the heterosexual MSW. Having unprotected anal sexual behavior (a OR=2.94, 95 %CI: 1.17-7.37), having group anal sex (a OR=4.08, 95 %CI:1.05-15.81), without record on HIV testing (a OR=6.58, 95 %CI: 2.01-18.06) and syphilis tested positive (a OR=4.55, 95 %CI: 1.15-18.06) were risk factors associated with HIV among the homosexual MSW. Conclusions:High HIV prevalence was discovered among both heterosexual and homosexual MSW in Wuxi, China. Differences in sexual behaviors between these two groups should be considered when designing targeted HIV intervention programs for these populations.