Objective To study the reproductive health status among unmarried floating females in Dongguan city. Methods A self-administered questionnaire was used to collect the information about reproductive health among unmarried floating females in the department of gynaecology and obstetrics and department of dermatology and venerology of 5 general hospitals in Dongguan city. Results Premarital sexual behavior, gynecological diseases, sexually transmitted diseases were reported in 23.71%, 35.11% and 5.41% of 3509 young women. The prevalence of sexual behavior, vaginitis and cervicitis was significantly higher in senior group (>24 years old)than those in junior group (=24 years) (26.39% vs 21.16%; 21.25% vs 17.93%; 8.99% vs 6.85%), but the induced abortion rate in junior group was superior to that in senior group (32.50% vs 23.72%). The morbidity of vaginitis, pelvic inflammatory disease and menoxenia increased remarkably in the females with sexual behavior compared with those without sexual behavior (29.33% vs 16.51%; 7.21% vs 1.16%; 16.47% vs 1.53%). Conclusions There exists a high prevalence of premarital sexual behavior among the unmarried floating females in Dongguan city. Premarital sexual behavior reinforces the risk of sexually transmitted diseases and other genital disorders.