The goal of this study was to explore gender difference in HIV-related perceptions according to a social cognitive theory and sexual risk behaviors and to examine associations between mobility, sexual risk, and history of sexually transmitted diseases (STDs) among male and female migrants visiting STD clinics. A cross-sectional study among migrants visiting STD clinics in three large cities in China assessed HIV-related perceptions, sexual activity, condom use, and history of STDs was used. Among participants, 20% of women had ever sold sex and 33% of men had paid for sex. Women and men were similar in multiple partnerships in the last month (23% versus 22%), consistent condom use during last three sexual encounters (14% versus 15%), and a history of STDs (57% versus 53%). However, more women who reported a history of STDs had contracted at least two STDs than men (55% versus 36%, p < 0.001). Increased sexual risk was associated with increased perception of extrinsic rewards for both genders, but was associated with increased perceptions of intrinsic rewards and response cost in women only, and with decreased perceptions of vulnerability and response efficacy in men only. High mobility was associated with increased sexual risk in women. Self-reported history of STDs was associated with a high rate of past multiple partnership and low education among both genders, but was associated with high mobility and commercial sex in women only. Fifty-four percent of women with a history of STDs informed their partners about their infections, compared to 36% of men (p < 0.001). Married women, both women and men who did not engage in commercial sex, and women and men who used condoms were more likely to inform their partners about their STD infections. Gender differences in HIV-related perceptions and sexual behaviors underscore the importance of gender-specific intervention efforts to prevent the spread of HIV/STD in China.