Abstract: Objective To understand the prevalence of AIDS and other sexual transmitted diseases among female sex workers (FSWs) and related risk factors in Mile, Yunnan province, provide scientific evidence for the evaluation of AIDS prevention and control and development of intervention strategies. Methods Questionnaire survey was conducted among FSWs in Mile during June-July from 2010 to 2012 to collect their behavior information. Blood samples were taken from them to detect HIV and syphilis antibodies. Results Among 600 FSWs surveyed, those worked in hotel/nightclub accounted for 33.7%, in singing hall/beauty salon accounted for 51.7% and street FSWs accounted for 14.7%. The average client numbers of them in the past week were 12.01, 14.67 and 28.88 respectively, and the condom use rates of them during the past month were 87.62%, 84.19% and 56.82% respectively. The infection rate of HIV and the prevalence of syphilis in three group FSWs were 1.49%, 2.26%, and 9.09%, 0.50%, 0.32% and 6.82% respectively. The prevalence of other STDs during the past year were 6.93%, 4.52% and 19.32% respectively. Conclusion The low grade FSWs had more commercial sex than others in Mile, but they less likely to use condoms and had higher HIV infection rate and STD prevalence, indicating the necessity to conduct intervention and prevention constantly among them.