Objective:To determine the epidemiological characteristics and incidence trends of sexually transmitted diseases （STD） in Mengla County of Yunnan Province， and provide evidence for future prevention and control of STD. Methods:STD case information from 2005 to 2017 was extracted from the National Notifiable Infectious Disease Report Information System. Data were collected by year and disease type，and the incidence rate， epidemic characteristics and suspicious contact history of STD were statistically analyzed. Results:A total of 1 251 STD cases were reported in Mengla county from 2005 to 2017， including 490 gonorrhea， 483 syphilis， 216 condyloma acuminatum， 16 genital chlamydial infection and 46 genital herpes. The average annual incidence of STD was 35.57/100 000. The majority of STD cases were 20-29 years old （n=541，43.25%）， married （n=603，48.20%）， Han people （n=638，50.10%）， with education of middle school （n=536，42.85%）， and occupation of farmers （n=702， 56.12%）. The 42.61% of STD cases had non-marital sexual contact history， in which the proportion was significantly higher among male （55.05%） than female （28.98%）. In addition， the proportion of non-marital sex among STD cases increased gradually by year and significantly differed. Conclusion:The epidemic status of STD in Mengla county is relatively low. However， STD incidence increased gradually by year， which warrants more and specific measures on the STD control and prevention.