Abstract: Objective To find out the characteristics of sexual behavior and HIV infection among women in clandestine prostitution and make easy to conduct STD/AIDS surveillance and take effective intervention measures. Methods The investigation was made anonymously among 113 women engaging in clandestine prostitution with the same questionnaires including characteristics of sexual behavior, condom use and history of drug abuse. Results The youngest women was 17 years old. The activies of prostitution mainly took place in beauty parlors,hotels,and restaurants.34.51% of the women had the first sexual intercourse,and 17.70% of them were younger than 19 years old.The proportion of women who went flow place to place in other provinces was 86.73%(98/113).The longest time of their engaging in prostitution was ten years.The number of people than they had sex within a day reached up to 20.15%(18/113) of the women seldom used condom.One person had been infected HIV.Conclusion There were high risk behaviors among women engaging in clandestine prostitution for spreading HIV.There fore ,it was necessary for govemment to strengthen health education and implement the intervention measurement to prevent HIV/AIDS transmission.