ABSTRACT: Objective: This study was designed to assess the prevalence of reproductive tract infections (RTIs) among an internal-migrant population of reproductive age in China. We also analyzed the knowledge, attitude, and practices related to these infections. Methods: A cross-sectional study using the quota-sampling method was conducted in three cities from March 2016 to February 2017. A total of 3320 participants (40.7% men and 59.3% women) were enrolled in the study, of whom, 1124, 1015, and 1181 were from Yinchuan, Urumchi, and Shanghai, respectively. Data on the included subjects were collected using a self-administered questionnaire. Results: We found that 3.2% and 22.6% of all subjects lacked knowledge regarding the identification and prevention of RTIs, respectively. More than 80% of the participants approved of developing RTI surveillance and taking RTI-related courses. While 45.1% of the respondents changed their underwear every 2⁻3 days, 49.0% cleaned their genitals daily, and 34.9% reported taking a bath daily. Among contraceptive users, 47.4% and 29.7% used condoms and IUDs (intrauterine devices), respectively. Overall, 48.2% of the participants had laboratory-confirmed sexually transmitted infections, and 19.7% of the female participants had endogenous infections. After controlling the socio-demographic variables, participants who cleaned their genitals and took a bath less frequently, as well as used condoms or pills had a lower prevalence of sexually transmitted infections, while those who were unwilling to take RTI-related courses and changed their underwear less frequently were more likely to contract sexually transmitted infections. While women who were unwilling to take RTI-related courses had a lower prevalence of endogenous infections, those with more children had a higher prevalence. Conclusion: The status of RTIs among the internal-migrant population of reproductive-age is not optimistic and is related to multiple factors. We believe this study will contribute to improving the knowledge, attitude, and practices related to RTIs.