Objective To understand the syphilis infection status of high-risk population in Yangdu district of Yancheng city so as to provide a scientific basis for preventive and intervention measures.Methods Serum anti-TP antibody was detected by the en-zyme-linked immunosorbent assays(ELISA).Treponema pallidum particle agglutination(TPPA)assay was carried out on the posi-tive samples of anti-TP antibody,then rapid plasma regain(RPR)was conducted on the positive ones.Results The syphilis antibody positive rate of high-risk population was 14.30%,among them the positive rate of RPR in the syphilis infected persons was 58.18%;the positive rate of syphilis had statistically significant difference between genders in different crowds and different age groups(P <0.05).Conclusion The syphilis infection rate of high-risk population in Yandu district is high.The infection rates of STD clinic clients and the people subjected to reeducation were higher than those of the person accepting voluntary counseling and testing(VCT);the infection rate of 21-40 years old females is significantly higher than that of males.The high-risk population mo-nitoring should be strengthened and the publicity and education and behavior intervention should be carried out to effectively re-strain the spread of syphilis in crowds.