Abstract: The data of reported syphilis cases were researched in national infectious disease monitoring system from 2016 to 2018. Five duplicated checking methods according to 7 indicators (ID card number, name, gender, age, date of birth, telephone number, current address code) were used and the duplicated checking was performed with SPSS 17.0. Results showed the duplicated reporting rates of syphilis in 2016, 2017, 2018 were 5.65%, 5.91%, and 5.85% and the syphilis morbidity rates were 37.1427/100000, 41.9059/100000 and 40.8918/100000. After the reporting was corrected, the morbidity decreased to 35.0444/100000, 39.4311/100000 and 38.4977/100000. The duplicated reporting rate was 8.28% between the year 2016 and 2017, and was 9.64% between the year 2017 and 2018. The duplicated reporting rates were higher in primary and secondary syphilis than in latent syphilis. The duplicated reporting rates were higher in primary hospital or maternal and child health hospitals than in general hospitals.

Key words: syphilis, disease surveillance, duplicate reporting