Abstract: Objective To evaluate the effect of AIDS klowledge,attitude and practice(KAP)among sexually active population in Shenzhen and provide the strategy for AIDS prevention.Methods A self-administered questionnaire on ATDS was used randomly among sexually active population whom worked in public services and were in Shenzhen for at lease one year as well as aged 16-40,and the outcome was compared.Results Difference of the knowledge of person with HIV infect may appear health,taking drugs or injections cannot prevent AIDS,the bites by mosquito cannot transmit AIDS(P<0.01)and shaking hands and eating together cannot transmit AIDS increased(P<0.05).The use rate of condom was 38.7% after intervention,which lowered than that(40.2%)before intervention.The multiple sexual partners and commertcial sex accounted for 46.5% and 56.9%,before and after intervene respectively,increased 10.4%(P<0.05).Conclusion It also presumed the increasing of the multiple sexual pattners and commercial sex accounting.It was extremely urgent to raise the use rate of condom and reduce the blind optimism.